LEO's have a chance of preventing you being robbed through proactive patrols when they are not writing tickets. And LEO's have a chance of catching the suspect fleeing from the scene when they are proactively patrolling instead of writing tickets. So it boils down to protecting people versus protecting property. It appears you would rather have the police protect your windshield and let the citizens fend for themselves.
So, you are pretty much saying LEO's drive around for a presence to stop a "potential" robbery but let these things go unpunished. I cannot enforce the laws, that's what we pay LEO's to do.
Had I been robbed I'd be out less than $250! And the perp may have a 9mm bullet wedged in his torso.....