I used public transportation less when it was free here in Seattle because it felt less safe. The buses have improved a lot since Seattle started enforcing fare collection again, and a few dollars isn’t much compared to not getting stabbed by some drug addict having a fent crisis.

Switzerland is different though: you know the police aren’t going to put up with crap at all (and they will arrive fairly quickly if there is an incident), so free could really work. Although I was never tempted to drive while living in Switzerland (in the next city over from Geneva). I don’t think free works in the USA however.