Something like 90% of burglaries are looking for car keys. That's why I keep my keys by the front door in eyesight on anyone who comes in. I have insurance, and don't want a thug wandering around my house.
I have the opposite approach when parking my car in San Francisco, I just leave the doors unlocked so they don't smash my window. I don't mind if they want to rummage around and find nothing but some old taco bell napkins.