If the real Superman really showed up one day the facts of life would make it more difficult for him. Like on the old television show, the bullets would bounce off his chest while he stood there laughing but he ducked when the pistol was thrown at him.
Also, anyone traveling through the air that fast to catch a robber would have bird guts and feathers hanging all over them.
Of course, they would make him looked scarier.
-Bill The Duck