I've had this happen at a large city in the midwest US.
They basically said, "most people here will break into your car. give us a few bucks and we'll make sure no one does." I didn't want to, but I figured its a few bucks and gave them it.
I got out of the concert and went back to my car. They were still walking around. They ran up and talked to us a bit, said nothing happened, thanked us again for the money and offered us a hamburger from McDonalds.
I'm not sure if they were "good" guys or bad guys yet, but they are around.
Back in the 90s this would routinely happen at English football grounds. The ‘watchers’ were the local kids - at Roker Park in Sunderland, in my case.
The point is that your car is guaranteed to be scratched if you don’t pay the fee.
This so much in South Africa.
Thanks to Lyft and Uber, I rarely drive when I'm in cities anymore, so I don't know if it's still a thing in the U.S.