[smileysteve]

But to give a free ticket, you still have to have the enforcement; you still have to use resources from the local government (to collect fines).

If you don't pay for enough enforcement (see NYC, Atlanta, Bart, etc that aren't free and have plenty of broken windows), then you still have a "broken window", only it has cost the system significantly more than your other opportunities, ie, armed security on the trains instead of staring at turnstiles; some positions may even be cheaper than your credit card fees on your profitable customers, less ridership (tourism, can't find card, uber competitor) because of fees and complexities reduces effectiveness of the system.