Lateral Thinking Puzzle #2

I think I'm going to make this a Friday feature. James has Shotgun. I'll have my puzzles. Anyway, violent, maladjusted Bob is back. He was the screen slasher in puzzle one. What's he up to today? Let's find out in this week's puzzle, entitled "Smashed Taillights".

Later, Bob picked up a tire wrench and smashed the taillights of a car he had never seen before. Police officers witnessed his act and arrested not him, but the owner of the car. Explain.