I'm not sure if it's a fact but that's what I have heard but not had any confirmation.

I shouldn't say trouble, but more correctly an additional fine because the person is trying to remove the mark off their car to potentially "reset" the time they were in the lot. So if another officer comes along (different than the first), and marks the car (supposedly for the second hour), there would only be one mark which is the new one because the previous one had been "erased" from what the first officer did.

you have to pay it either way, when you renew your license

No you don't.