What's the difference between this and completely free rides? AFAIK, making it "almost free" is usually preferable, as it prevents some abuse ("it's free so I'll take it even when I don't really need it", which depletes the resource), while still making it effectively free.
We've also seen the opposite being true. In Germany, oddly enough. It was called "Praxisgebühr" and it was a 10€ fee that you had to pay once per quarter year (if you went to a doctor in that quarter). Turns out, once people paid the 10€ they got into a all-you-can-eat frenzy and visited more doctors than they normally would have done, because "well, I paid for it, so might as well take advantage of it".
We have a system where you're going to pay about 350 per year for those little things if you use them. Going into a frenzy using all of that is just going to waste your own time as it takes quite some effort to use up that 350 already.
Then again, regardless of the rules and processes we make, there will always be people misusing/abusing it.
Remember that even if the journeys are 'free' in the sense of money, they still take time. And for most people sitting on a bumpy bus isn't as comfortable as sitting at home or sitting in a park (also free ways to spend time).
You should always think of the cost of public transport as ticket price + hourly wage * time spent - value of anything you might get done on the bus.
This is true for busses, but train rides can be quite enjoyable on their own to some people, depending on the train and the view. You still have the opportunity cost of everything else you could be doing, but some people might prefer to read the newspaper on the train, enjoying some shopping a couple towns over and reading on the way back.
