At least in my car, I'm guaranteed to not run into weirdos or gross conditions caused by ill adjusted members of society.
Unfortunately, we are completely surrounded by gross conditions caused by ill adjusted members of society. Those individuals just happen to be in the government.
Unfortunately that falls under a different category. Fuck cars is about advocating for good public transportation and making cities easy to enjoy without a car. You're asking for better mental health care and services for the homeless. There are very few people that would actively do this type of thing if they had any other well lit up space they could do it.
If you are so scared of other people to the point that you refuse to use public transport then you are just paranoid. Crazy pictures and videos taken on public transport are just extreme examples, not the general everyday experience of using public transport.