Because slashing tires damages so much less than calling the police. Come on ...
I agree, fat people should not be given handicapped stickers. I worked at a grocery store through high school and uni for 2 years (in the US) and you won't believe some of the shit I saw people do. Trust me, humanity sucks when it comes to the grocery store.
But Phish, that is no $200k car. That's a simple 911 Cabriolet (probably not even a 997). Big fucking whup. Even if that car was fully-kitted out, it still wouldn't cost $100k unless there is a huge markup from the dealer. If you are worried about getting your car scratched, you do what my friend did: park far away from everyone else.
It's not even so much the argument of calling the cops or slashing tires or whatever: it's that people that truly need those spaces, typically have to struggle to get to the door and always worry if there isn't an available wheelchair. It's also something different to go IN empty handed and come out with a full load and then have to load it up. The worst part is that people that take those spaces are just showing how inconsiderate of those less fortunate than themselves.
But if you're fat and get a handicapped sticker: fuck off.