Or, well, to make SOME of it free.
If you make certain train lines, busses, etc. free, it acts as a magnet for certain “undesirables”, thus allowing the rest of the population to travel in peace.

> acts as a magnet for certain “undesirables”
Or you can enforce the laws and throw these criminals in jail and insane asylums forever if they claim to be insane to get out of a crime