They're not, and it's not really an HN thing to respond like you did. The guidelines ask you to assume best intent and engage in good faith.

Here good faith curiosity would have led you to where peer replies are pointing you: that free transit in big metros tends to come with loitering issues, and if they become too extreme, it can make the transit system pretty inhospitable and uninviting for the families and working people meant to be using it, undermining the purpose of making it free.

It's a genuine challenge that metros of a certain scale need to address, although the OP is maybe (or maybe not) wrong in assuming that it would be an issue in a fairly small/high-trust college metro like Iowa City. But, in best interpretation of their comment, that's why they were asking it as a question.