I learned this lesson early on in life. My (then gf) and i parked opposite a police station parking lot, i'm serious, if i had a bit of phelm i could have spit on the station doorsteps. We left our bags on the passenger side, like always. Afterwards, window was broken into and our bookbags gone. Yea this was in early 2000, before electronics were really that portable. (you had to be really well off to have a lap top back then) So they just stole all our college books, and notes and ****. and gym clothes, literally walked across the street and reported it to the police.
Thieves are scum and will steal anything, anywhere, even 1 block away from a police station!
Ever since then we always put anything, ANYTHING of value in the trunk, when we had early GPS we took the whole thing, suction cup and all down and put it in the glove box, everytime, there's no money or change in the holder, our cars are clean as hell. (so they don't snoop around to see what they can steal)