Monday Madness-Stealing Gas Caps

I parked next to this car above the other day and thought; you can't ride around like this, especially nowadays. Thieves steal gas caps with the door on, so it's like this picture is saying, "free gas cap".

I thought about getting the one that locks, but didn't want to deal with the hassle of a key. Mine was stolen once and I think it's sad when someone has to stoop to a low to steal a gas cap. They're not even that expensive, for under 15 bucks you can get one at Pep Boys.

What's worse is that I was driving around without a cap for I don't know how long. I'm surprised nothing major happened or the 'check engine' light didn't come on. A gas attendant told me it was missing. Now I'm thinking was somebody trying to steal my gas?