You're the kind of person who questions the use of super powers in comic book movies, aren't you? [izzat so?]
It's entertainment. It's not supposed to be real. You might as well be asking why wrestlers aren't arrested for assault and batter after matches. It's no more far fetched than things you'd see on other TV shows or movies. It's called suspension of disbelief. If you can't suspend it over the use of a sledgehammer, then how in the hell can even watch wrestling?