I can imagine some benefits if it worked flawlessly and I know some railway stations operate on a request basis, but on the face of it this strikes me as being a similarly ridiculous argument as saying in urban areas drivers waiting in a queue of buses should be allowed to load passengers away from a bus stop.
In my opinion a bus stop is either a mutually recognised location for both drivers and passengers or the stretch of road is designated as a 'hail & ride'.
Other than for requesting special assistance I don't see this catching on. Most folk can understand the need to ring the bell inside the bus when a passenger wants off, but not the other way round.
I have an example near me on the A41 near Backford. The bus needs to be in the right hand lane to turn right but because of the flow of traffic, buses try to move over as early as possible. If someone is at the bus stop close to the lights though, the bus then bypasses them or crosses over but it's time consuming. IF you wait to change lanes until you are at the bus stop, quite often people won't let you in because you are at zero and the road speed is like 40 so it would potentially put yourself and drivers behind at risk.
The way to combat this issue would be a signal so that if someone wanted the bus, they can get on but it doesn't needlessly delay every single bus on a 'just in case' basis.
Chester Zoo is another one. Out of opening hours, workers still want to use the buses but can't because it was delaying so many buses with no one boarding. A signal in this instance would add delay to a few trips where people were waiting but it wouldn't needlessly delay everyone else on other trips (which is the reason the times were changed to speed up journeys for the majority as demand wasn't always there and varied by day.
In Merseyside, Arriva wanted to drop Ince Blundell village to speed up journeys by 2 minutes. They wanted to run along the main road. If this signal type system was introduced, Arriva could bypass the village when no one was waiting but then divert in if people were waiting.
As well as villages just off the main road, I can see this working at tourist attractions with bus stops because the demand can vary so much (by weather, day of the week, school day/holidays and opening hours), this would help operators divert just off the main road to serve these stops when people are waiting (
Legoland Windsor for example (Greenline 702/703) or
Presthaven Sands (Arriva Rhyl 11 series).
This won't work when you would risk missing out lots of stops but one stop here and there can add on a few minutes to journey times. IF you can speed up the majority of journeys, operators will. A 2 minute diversion can be caught up in a fair few cases so it would make little difference but not a lot is more annoying than going around a 1 stop village, attraction or estate to then find out no one is waiting.
