I just want to make reference to the BART revenue officers - who appear from your posts to delay a train service when they are checking if all the passengers have a valid ticket.

In Sydney Australia - I am familiar with their system.

The Transport Authority works hand in hand with a police division called Public Transport Command.

They patrol transit station (railway and bus) and check that everyone is using the correct process at the barriers, but they also do spot checks on trains and bus's . What they do is get on a train or bus and travel with that train or bus, while checking tickets are valid and that anyone using a concession is entitled to that concession. Once they have checked everyone they get off at the next station or stop - and get on another service.

This way they do not delay any services. Something BART could learn from