Lots of questions...
-The device looks rather flimsy. Just push it out of the way.
-Are there devices for every parking space? Or is this something you put in your trunk and leave in an open space?
-If it is wireless, it can be hacked.
-Are there explosives attached???
Probably too much. My business model would be much cheaper:
Hire homeless people to lay down in a parking space and pay them with their preferred drug of choice.
Like the guy in Manhattan who had the fake fire hydrant? He'd set it at the curb and drive away; when he returned he'd park and put it back in the trunk.
(Urban legend?)