Why do people think it's amusing to run their car tires over freshly painted yellow lines?

I didn’t know this was such a problem it needed to be addressed lol. I assume for the same reason anyone does anything mischievous.

Sometimes it’s an accident.

i will restore some of your faith in humanity. Not all those marks are not malicious. Sometimes people are passing or moving to the other lane before the paint dried completely. There might be something blocking one edge of the road and cars need to go around it. There is little to be gained by a malicious driver since they cannot see their handiwork.

Now here’s another tidbit to restore your faith.
Disclaimer: the following statements are totally false. This is pure fiction. (Since it it were true someone would get into trouble.)
Back when traffic “cones” used to be 55 gallon metal drums painted orange and white, some individuals would enjoy hitting them with their cars and sending them flying down the embankment. The guys at the DPW would have to go out and replace them again and again and they got a little frustrated. (Not to mention wasting taxpayers’ money on vandalism.) One day, the guys filled a couple of the drums with water. When they came to inspect the site the next day, some of the empty drums were gone, as usual, but there were a lot of car parts, and broken glass where the full drums had been.
They did not have a problem after that and no accident report was ever filed.
Theoretically speaking of course.

Assuming it’s on purpose? Arrested development. The same people drive trucks through puddles to see how much splash they can make. They still think 6th grade jokes are the funniest thing they ever heard. They’ve never grown up.

I don’t know but I think it’s amusing they don’t care about their cars enough to chance getting paint up underneath and alongside their running boards and tires/wheels.

What’s not to like? I mean, how often do you get to get creative and paint with your car? ;-)