In this city theres a train line that services the city north-south. For paying for fares there are two options: one is buying a card that has four rides worth of value on it. The other (for citizens) is to buy a card you can recharge). You buy these at booths from people inside the station building/area. The four-rides option is a plastic credit-card style card.
To enter the train terminal, there are turnstyles with card readers. You place your card against the reader. A screen beside it displays how much value you are charged and how much remains. If it is the last of four rides, it tells you to insert the card (instead of keeping it in your hand as you enter). Then the turnstyle is unlocked and you pass through. There are transit workers here which can see no one is jumping over the turnstyle.
Now you ride the train as much as you want until you exit a turnstyle at any station. There is a flat rate for taking the train anywhere and for any amount of time. You do not scan your card when you exit. You just exit. Therefore if you lost your ticket on the train you wont have a problem exiting.
The security workers for the train are therefore not tasked with 'policing' or 'checking tickets.' There is no uncomfortable and irritating ticket checks. There are no fines or the cost of processing fines. The workers who would be checking tickets and 'policing' in my country are here allowed to service the customers ie offer information and directions when asked and ensure physical safety and security.
The experience is easier and more comfortable and less aggravating. The cost of running this type of system appears to be much less because it involves less problems to have to deal with and perhaps less workers - in any case, the workers appeared to me of more value than the 'ticket checkers' etc in my country's city trains.