True. In fact, it's even stranger in the UK, or so I'm told...

Trains have drivers. Some stations have shorter platforms than others. Thus at those stations a smaller number of train doors need to open to allow passengers on and off - as some doors won't be next to a platform, they'll be above fresh air.

You could have a 'open all doors' button and a 'open <x> doors' button. But the driver is not trusted to do this, so instead there is a GPS on board so the train 'knows' where it is, and opens the appropriate number when the button is pressed.

I think in London, certainly for the underground, the lack of driverless trains is more to do with strong unions than it is safety perceptions (the DLR line is driverless). E.g:

http://www.telegraph.co.uk/news/uknews/road-and-rail-transpo...

"Unions have fiercely opposed the introduction of driverless technology on the tube, with the Aslef drivers’ union threatening “all out war”, but the Mayor said drivers would not lose their jobs because "train captains" will still be required."

Train captains! :-)

Though that doesn't mean that risk perception doesn't cause us to make other poor decisions. The UK had some rather bad train accidents (again, human error with 'signal passed at danger'- see http://en.wikipedia.org/wiki/Signal_passed_at_danger). Politicians get involved - and phrases like "this must never happen again" get pushed around, and huge cost estimates for the engineering required to chase this improbable 100% 'never again' target (>£1bn in 1988) are submitted. This inevitably delays implementation (if it ever works anyway - governments and big systems after all) - when we could be doing something simple (GPS is a thing. Trains move only in one dimension, and don't suddenly reverse direction. Finite number of tracks. Build system monitor for "train about to hit another train") that gives you 80/20.