Universities and FE Colleges are a similar market, with less clearly defined start and end times.
I'm not sure what point you were trying to make with schools traffic. Schools services are increasingly run commercially- GNE run several on a commercial basis. Operators will run marginal estate or town services during the daytime with off-duty schools vehicles. Were you intending to combine normal service buses and school buses? If that's the case, I'm not sure who you'd be hoping to attract with a bus full of schoolkids?
Unis and colleges I would argue are completely different. Universities generally have varied start and finish times with students living on or close to the campus. Colleges have students travel sometimes for around an hour and a half to get to the college with the start and end times pretty set (there is some flexibility for students but college buses tend to do just 1 return trip with all buses leaving and arriving at site around the same time.
Schools, it depends on the borough and the operator. There are commercial school runs, plenty of them. There's also a LOT of non school buses. some examples of where you could merge routes are if there are only 30 odd kids going to the school and you have an Eclipse, you have more seats than kids so there is available capacity for regular passengers to make local trips. Cheshire West and Chester do this on both the 61 and the 22 tenders. If you have a double decker full of kids, you are right that you won't get many 'normal' passengers onboard. Also if you work with the school, it might work out that if you only duplicate part of a route, it means you only get a 15 or so kids onboard that bus and the school can then divert their bus to another area or link areas onto 1 bus rather than 2 to reduce their overall expenditure.
If you were to have a double decker bus full of kids, I know operators who make all their money on the schools with the services just being pocket money so while it may be inconvenient serving a school and having 2 trips per day full of kids, it can help to boost the overall route revenue to such a stage that the through the day profits don't matter as much (of course all trips should make money but if a company wants 40k profit per bus, per year, the school might go a significant way towards that).
It really does depend on the types of employers on those sites. Take your point on Omega. They have a service from Warrington that is pump primed by the developer. However, Omega from its further occupancy to now they took time to achieve that critical mass over a number of years. Again, if it were your business, when would you go in? Day 1 and lose money immediately or wait and see how it develops (whilst risking that people will simply make other arrangements). It's difficult (as with large housing developments) to time the entry in which is why s106 funding is often used to pump prime operations, and is a condition of planning. It really isn't straightforward. As an aside, those sites with the biggest workforces and largest potential customer base are often the major grocery or eCommerce facilities that are headcount hungry yet have the greatest seasonality and variation in usage with agency labour.
If I take an example closer to where I now live, Severn Beach has some large employers but draws its workforce from across Bristol, South Wales, South Glos - it's a nightmare to know what you run, from where and when. At least there are some employers that are easier to serve in Bristol and yes, they have services albeit as contracts as simply, the revenue wouldn't cover the costs.
Omega has only been going for 5 years and the service has been commercial for at least a year or so possibly more). At the distribution parks, you will lose money on day 1 (as per ALL routes regardless where they go). You work with the staff though and if possible promote the service within the park to the staff. S106 is a great funding system for buses but it isn't requested enough in my opinion for these types of development.
I think the main reasons why the Omega bus has worked and it could be done elsewhere is that many of the companies have the normal industrial shift times (6am-2pm-10pm) so the bus goes around all of the sites around that time so while each facility on it's own might not sustain the numbers, combined, you have a bus full.
Severn Beach is harder as you say with the workforce catchment area and the sites all being spread out. As with housing developments, each out of town employment area (business or industrial park) needs to be judged on it's own merits since none are the same.
I take what you say and if an operator can easily do so. I don't know which Transdev examples you're thinking of but take St James in Knaresborough. That gets a half hourly service as part of the 1 (plus Connexxions X1). It's large but it's no White Rose Centre and I doubt that it's going to sustain anything more than that.
Coastliner missing out Seacroft. York Designer Outlet (Normally these have big young people demand from big cities. Cheshire Oaks for example has huge student demand from Liverpool). Boundary Outlet in Colne.
Colleges are more difficult. Truro is a good example where they do divert some services but it also has to have a great number of dedicated services. There are some areas where a local bus can be diverted in but often you have a disparate number of locations running to a central point for 0900 and then the return at 1700. Such a network has to be underpinned by the college as a commercial venture just isn't sustainable. Again back to Yorkshire, York College has routes running in from Northallerton, Scarborough, Goole, Sherburn, Ripon, Filey, Kirkbymoorside - it's a nightmare. Operators are increasingly working with Colleges to have a network but speculative commercial punts are just not sustainable.
Oh yes, I agree there will always be some areas which need dedicated college/school buses but if you can work it into a service route, there is potential there to make it more viable. Commercial negotiations with college funding (normally by purchasing tickets for students on the service) could make things work. As you say it needs a route to run longer term but if you have guaranteed usage, it will help to boost the viability and hopefully make the route last longer.
Each bus you put on the road needs to make >£100k a year. New services are a risk when you're only making £1.4m as Transdev did. If it were simple, wouldn't everyone be doing it and raking in the cash?
New services are a risk and yes an additional bus does require a lot of money to run and that is why you have to make so many negotiations and link up routes in such a way to make the route have as much chance of working as possible. If you just put a route on and rely solely on 'normal' passengers, you will be waiting a year plus for the route to break even. Adding in the students (colleges or high schools) and the commuters (where appropriate), you can perhaps reach break even in a few months which is of course much faster.
The issue with new routes is that it could financially cripple them if it goes badly wrong (as in the case of Zap MCR). If the new routes which did pop up had better negotiations done with the relevant authorities with the potential funding which I have mentioned, some services around the UK might have been kept longer. You can rake in the cash but for that, you need to play the waiting game and bus operators don't like that. They want high profits almost straight away with breaking even after a few months generally being unacceptable. Why spend money on a route where it will take a year to make money when instead the money can stay as profit and you have lost nothing. Spend no money and lose nothing or spend money and risk winning or losing. The way I see it, that new route could become the busiest and most profitable route in the garage but you will never know because it wasn't tried.
Transdev have some avenues they could look at but I don't think anyone is in a position right now to start new routes, the focus is very much on getting back to normal and recouping as much lost revenue as possible from the past year.