That is true. I've used the computer controlled metros in Paris often enough and there don't seem to be too many problems but I suppose there are guards around

That is true. I've used the computer controlled metros in Paris often enough and there don't seem to be too many problems but I suppose there are guards around. As for buses, I find there are two cultures, either the bus driver has some amount of responsibility for what happens on board his vehicle, answering commuter questions, announcing stops, checking tickets etc., or he completely dissociates, and just drives, sometimes not even being the one to check your ticket. In the latter case you tend to have a lot more theft no buses. (In my limited experience. I'd love to see data on that, actually.. although the distinction is perhaps a bit hard to define.)