This because thieves don't know what's in the bag. Could be clothes or a laptop for all they know.

Also make sure no one is around when you hide things in your car. I hid all my shit when I went running on Blackstone Boulevard a couple of years ago and still had my car broken into. I suspect the thieves might have seen me while I was hiding stuff because nothing was visible from outside the car. My phone and wallet was stolen but I actually managed to find the phone... in a trash bin further up the Boulevard.

I linked my phone's location to my Google account, and luckily my phone was still powered on.