On a societal level, I think more “normal people” would take public transit if they could guarantee the removal of homeless people and people behaving antisocially
Are you proposing any specific laws to manage antisocial behavior?
In the end, I'm certain that the better idea is to simply give people jobs.
Actions like smoking/vaping, busking, drug use, littering, and peddling are usually already illegal in public transit, but widespread and difficult to enforce.