Because K9 unit vehicles are modified for the dogs.
They are climate controlled at all times and the better ones even have alarms that go off in case the car malfunctions, leaving the dog with no heat or AC.
The K9 officer I talked with one night was sweating to death on duty outside the car and his GSD was lounging in comfy cool splendor in the car on her bed with food and water in specially mounted bowls.
I’ve never seen such luxury accommodations here... cops just leave the cruiser motor running with the AC on. I’m all for it.