Not only will it cost the police more, but it also costs the car insurance and by proxy everyone that is insured.
If 100 people leave the car unlocked and are robbed and on average the car costs $30,000, this will cost $3,000,000 + insurance resource + customer hassle + police resources + judicial resources. That is a steep cost to all parties.
(Dis)incentives are more successful when it considers all actors.
'Smashing a window' is unlikely to incur costs of $30,000, perhaps $300 is a better estimate.
I would also argue that insurance resources, customer hassle, police resources and judicial resources are also all roughly equal for handling stolen items from a car, versus stolen items from a car + window broken.
You’re ignoring the fact that an unlocked door greatly increases the chance of the crime happening in the first place. It won’t cost more but it will make it happen more times.
Many opportunistic thieves will simply try the door and only go in if it opens.
In what world does a broken window total a car? While we're at it, in what world does your insurance premium not increase drastically after you collect on a claim? Your math is incredible flawed?
My example implies that some cars will be broken into for items that are in it while other cars will be taken by the assailant, the $30,000 example is for visual purposes. Do you expect all cars that are left open or broken into, to be just for a 'car stereo'? Do you expect all assailants to go to court and incurring the judicial cost I listed?
"As an example, while a simple automobile case may resolve quickly after case initiation and incur less than $10,000 in fees, the total costs of such a case can also exceed $100,000 per side if the case goes to trial." - IAALS.Du.EDU
If 100 people leave the car unlocked and are robbed and on average the car costs $30,000, this will cost $3,000,000 + insurance resource + customer hassle + police resources + judicial resources. That is a steep cost to all parties.
(Dis)incentives are more successful when it considers all actors.