So, if I read you right, you think that if a restriction says valid at or after 0930, it is still valid before 0930? You really should look more closely!
I did look more closely. The problem was that in my recent searches for valid trains at the fare I had travelled on I was using departures after Christmas and before New Year (when the fares rose), completely unaware that FGW had relaxed peak travel restrictions during this period. So all fare planners showed me earlier departures before 9:30 as being valid (subject to connections). I had mistakenly quoted restriction 8X instead of the one that applies, 5K.
If I try Brighton BTN to Bicester using NRE, it is unable to offer me any off-peak returns starting out before 10:34 AM unless I feed it routeing options that unless I had travelled that route or researched all the maps I might not know. RedSpottedHanky does better but does not offer a lower "not London" fare although the journey time is similar, unless I request that option. And once I've ticked the box for Not London it seems happy to sell me a ticket for the higher price via London without offering me any via London trains. If I go via London at the higher fare, I face a 30 minute walk from Bicester North to Bicester Town (yes I know trains from Oxford are not frequent). The same routing is offered with a disabled railcard, out of interest. When you choose an option, if you "hide options" the option - unknown to you - is still selected and that may cause it to offer no fares at all leaving you wondering why. I chose a valid 'via' Option that it could not handle, it needed a second 'via' Option but that's not possible.
It's all very unsatisfactory.
As to the point,
There is no simple solution to the problem of the fares structure (you're welcome to suggest something if you think there is). Journey planners are fairly basic tools for people to use, they are not perfect, but then most people just want the quickest, cheapest train journeys with the fewest changes of train possible, and that is actually quite hard to do in some cases.
I simply do not agree. Yes it's obviously hard for the existing computer software to do, that is abundantly clear.
Everything is rule based, with the exception of split tickets (a huge problem to program) and lends itself to an automated process. I am using highly sophisticated search tools to find fares, routes and stopovers on multiple airlines. By comparison, rail search facilities are primitive. They can and should be improved so that we can all stop wasting huge amounts of time searching for trains, routes, fares and restrictions. Then more people would travel. It can take longer to find one's way through this maze than to make the journey. Also, as I've seen, it's so easy to make mistakes along the way as the system is so uninformative and unintuitive.
In the case of the routeing on my ticket, the lowest fare is often not offered unless I insert at least two 'via' options. Most rail ticketing sites allow only one option. Requiring that I must compulsorily insert options (like 'via' stations that I might not know about) to find the cheapest fare I find absurd, yet I also want to be able to insert options of my choice like "avoid London" or "not via Clapham Junction". Yet if I am not familiar with the journey, why should I be expected to know the routes trains take in order to find the lowest fare?
I want to know the lowest fare to my destination and see if Im happy or not with the restrictions or routeings it imposes. Isn't that what the search engines should be offering me - suggesting different routeings yet allowing me (if I want) to select my own routeings or test if certain routeings are valid?
What we need is a system that is simple to use for those that just want to get from A to B while at the same time addressing the needs of people who want to go e.g. via Birmingham or break a journey en route perhaps for lunch, shopping or a short meeting. That's why Advanced options need to be powerful, offer multiple choices and work properly. Of course that requires investment, the usual UK obstacle.
As we have seen with Brighton to Bicester Town, it does a simply terrible job of helping me "simply get from A to B" or if I don't want that then it does an equally terrible job of exploring options like different routes and fares.