What type of scrutiny does your public transport system have?
One type makes the assumption that passengers are crooks and need to be prevented from cheating at all costs. Security gates for entry and exit are the norm. And then there is additional security to ensure that these gates aren’t circumvented or vandalized. When trust is low, every customer has to be checked, surveillance is costly and the system is inefficient.
Another type of system trusts people to behave themselves. Passengers walk into trains and trams without any scrutiny. However, a handful of people perform random checks, and once a person is caught travelling without a ticket the fine is quite hefty. This system is efficient – a handful of people keep the entire system functioning by dissuading the detractors.
Needless to say, the lightweight system of random checks requires a certain amount of trust in the system. If travelling without a ticket were the norm, it would quickly cease to function.
Self-monitoring is efficient. Besides, the freedom it gives us inspires us to be better people.