[danarmak]

That's more expensive because the cost (installation and servicing) scales with the number of bus stops.

Also, there are things you want to do that this doesn't cover. For example, announcing the next stop when you pull away from the last stop.

[Crosseye_Jack]

The announcing the next stop could be achieved with a dual radio setup, one high powered and low powered. The high powered could be used to detect an upcoming stop and the low powered could be used to detect proximity to the stop.

(Lets ignore the security issues that have been shown with amplifying the low powered radio in cars for a second) It's a method used in keyless entry in cars. A higher powered radio is used for button press on the cars key so you can unlock the car/open the boot/sound the horn to locate the car at a distance but keyless unlock should only work at a much closer distance.

Not saying its the correct way to do it (my local bus network doesn't do this) but stop proximity can be worked into their idea.