I don't know how it works in your country, but in mine enforcement of rules on busses is pretty patchy.

After all, do you deny boarding to people who look like they might break the rules? Ask them nicely to disembark if they start? Have the driver manhandle them off? Stop the bus and call the cops? Rely on scowls and tutting from other passengers?

With that said, I spent a few years riding busses in university, and didn't encounter problems from other passengers. Punctuality, service frequency, crowding and journey times were much bigger problems for me.

This is about civil rights, not the practicality of enforcement.

Rules? We have ceased to be a society of rules. (And soon we will stop being a society of rule followers, which will signal the end of our civilization, but that’s a different rant.) Here in DC, we won’t even enforce the “rule” that you have to pay the fare. Good luck enforcing anything else.

Haven't people been avoiding fares since the invention of fares?

Most people don’t avoid fares. I’m of the view that the point of criminal law isn’t deterrence as such, but rather norm setting. We punish people for fare evasion so people know it’s a bad thing. The norm keeps most people from evading the date. But when you stop punishing people for it, the norm is diminished.