I'm hardly liberal myself, but what sort of policy is it that you imagine could change this at this late date? Cops could be directed to arresting such people

I'm hardly liberal myself, but what sort of policy is it that you imagine could change this at this late date? Cops could be directed to arresting such people aggressively, as their primary duty. Prosecution could be greased such that they aren't getting back out pre-trial... at least temporarily. Laws might even be modified such that they are convicted. But at the end of the day, you need to warehouse them somewhere if you're going to keep them off the train and from stealing hats off people's heads. And in the places where this is the biggest problem (California), they're constantly running into prison capacity issues that see people released early. All this remains true even if your jackbooted enough to be willing to go through with this crap. There are some other fundamental issues that would need to be solved first, and I'm not even certain those have been identified.