NYC: why do they say dont leave receipt in car

after parking and going to the elevator to the terminal, the sign said dont leave your parking receipt in your car. what good is a 280 receipt? i dont think any personal info is on there.

do people break windows to try to reuse them or something?:confused:

I believe thieves use them to get your car out of the parking lot and steal it.

how would that work. i'm assuming they wont let me thru the gate unless i paid initially? and when i left no one checked my receipt.