They do it because they can.
If you caught someone doing it what can you do?
Kick the living sh!t out of them.
2 dodgy tw@ts tried to break into the house I was living in many years ago, old misses was pregnant, she lost the kid through trauma etc, long story but one of em scampered when I got downstairs to see what the noises were, the other I got and gave him a proper going over. You know what happened ? I got 200 hours community service. Judge said the right thing for me to do was to call the police and wait.

Point of me telling you that ? If I caught someone scratching my car, I'd do the time (community service or jail) again for them no probs at all.