This would depend on first fixing the poverty and homelessness that make theft, vandalism and antisocial behaviour so common. These things cost money to protect them from the impact desperate people otherwise have on them.
Now, I’d be thrilled to help pay for that to all happen, but the order should be respected; making trains and buses free isn’t as simple as it sounds.
Also because when you are in separate cars, you can't get sick from, or harassed by, or groped by, other drivers. If another driver is bothering you, you can usually just speed up or slow down to increase distance.
To get true mass adoption of public transit in the US, as the parent comment said, you need to fix "the poverty and homelessness that make theft, vandalism and antisocial behaviour so common," or at least work around it. Maybe trains with a hundred doors leading to a hundred isolated seating areas would convince people.
How convenient for the car lobby that their luxuriously subsidized travel mode already excludes the poor, making them immune from this line of reasoning!
It might be expebsive, but it's definately as simple as it sounds.
I do not see how vandalism will be any different than it is today
Most bike thiefs are not homeless, especially high end bikes.
Not to many homeless have a bolt cutter in their worn packs, nor do they have a way to sell, or part out.
In my liberal wealthy enclave, it's middle class guys doing the stealing, or gangs.
(This whole blaming the homeless needs to stop. Most don't have the savy to steal a locked bike. Plus--riding a nice bike is a cop calling card. I know homeless guys who are afraid to carry their own prescriptions in their pack because they frisked so frequently.)