TramTrainBus ticket control
Is there any legal base to control a Tram/Train/Bus ticket outside vehicle? ( platform, bus stand) during ticket control at the tram stop, controllers are usually standing at the exit of the platform ( not in the tram) and forcing people to show tickets, otherwise they will not let them out ( always bulky lads are at the exits). Same thing at the train stations, but never at the bus stops. Logic says, that when i buy tram ticket, it can be checked on board only. Once I step out, no one should be asking. Is there any law that requires me, as a passenger, to show ticket outside vehicle?
Thank you in advance