Man, thieves suck! That's odd, and thankful that the perp left the other items behind though.
When I first moved to MI, friends used to laugh at me always locking everything; the front door when I stepped out. The car doors even when I was just running into the gas station briefly etc.
They'd laugh and tell me, "You're not in L.A. anymore, you know?". I told them, "A) old habits die hard, and B) better safe than sorry". Every single one of those folks, over the past decades, has gotten into the habit of doing the same thing now.
Here's a really weird story though:
One of my friends in NY had a different experience. His apartment had no included parking, so he had to park his car on the street side. Over the years, he'd had the window smashed, and the stereo unit ripped out of the console twice.
I'm not sure how it started, but he began leaving the car doors unlocked, and nothing of value in the vehicle, and a bum began using his car as a bed at night.
He'd find small signs of it, but the bum didn't mess up the car, and was always gone by the time he had to go to work in the morning. After a while, he eventually replaced the stereo again (after it had been ripped out the 2nd time, he'd held off on replacing it), and continued leaving the doors unlocked.
The 3rd stereo remained in the car. He began doing stuff like leaving a wool blanket in the backseat in the winter, and occasionally leaving $5 - $10 folded in the blanket. The blanket was always folded back up, when he came down.
First, there was the 'Trunk Monkey', I guess he upgraded(?) to the 'Backseat Bum'.
I don't know if I'd want to do that with an expensive vehicle, and/or have to put up with 'Eau de Bum', but apparently, it worked for him until he eventually moved.