I still see children walking alone where I live, but I'll admit that I can't compare it to when I was young because I don't pass by elementary schools before/after school to be able to see them.

I could definitely see it championed by some conservative people. Both ends of the political spectrum can have tendencies towards government control, depending on the topic.

Conservatism is often built upon fear. Also consider all of the studies linking right-wing political views to physiological differences like bigger amygdalas (which play a role in fear).

Some people will be fearful that children need to be protected at all costs, so they'll do things like this.

Just remember which side is doing things "for the children" as a scapegoat...hide the gays for the children, no drag story time to protect the children, no sex education (even books) to keep the children innocent. No walking alone outside to protect the children.

I'm not saying this particular Karen was Conservative, but I'm saying that she could be. I'm not sure why you're blaming Liberal people, but I'm sure you have explanations like I do (and I'd be curious to hear them), but I'd wager that the problem is not exclusively tied to either side of the political spectrum.