There is a very large and rampant amount of bad behavior well below the "jail time" threshold. Even then, the police can't be everywhere all of the time.
Then your city has much larger problem. In my city, public transport is as safe as anywhere else. That is how most people get to work. And kids to school.
> There is a very large and rampant amount of bad behavior well below the "jail time" threshold.
Where? I don't see it in major cities I am in, and I take public transit regularly.