In China, there's no ticket checker in public buses. Certainly, it's not free but the fine is quite cheap and anyone who uses the bus will automatically put money in a box in the bus. I think that's great! Pity there are still so few examples.
Arale, this is a common thing in the Western world. Disabled people and students have the free tickets provided from the government or the school. However, those free tickets are bought from the taxes money. Thus, in a way, they pay for their own tickets. There is no free things in our society. To me, the unrealistic about the main communist idea is that things need to be shared. In capitalist society things are traded.
When you live in a society that things should be shared, it's hard to maintain. For once, there would be people who gave more than others, but everything had to be shared equally. Therefore, at the end they would be really disappointed for living in a society that they gave more and got the same amount as like others. In a society that things are traded people trade whatever they have to get something in a similar amount. If they don't have anything, they would trade to get what they need by working. To me, this is best system.