This article kind of sums up my feelings on breaking windows:
It's getting HOT in here, so.....bust out the windows of that car that isn't your's?* - Bravo Dogs
I think there are a lot of idiots out there and yes you absolutely should eyeball each situation carefully. But don't automatically assume that a dog in a car is "suffering" or go breaking any windows without knowing the facts. A LOT of cars have it to where you can turn the AC on from your keys even if they are not in the ignition. All my parents cars have this. There have been occasions when we run into Walgreens or CVS for example and leave the 3 dogs in the car while we are in there for 5-10 mins. If I came out to a broken window and 3 VERY stressed out dogs (Jackson does NOT like to be approached or touched by strangers, and our dog Buddy WOULD bite you) .. I would be pissed. And yes occasionally I do leave Jackson in the car because he's with me a LOT... I travel between houses often and it's simply not always feasible to drop him off first and then go somewhere after. Now I won't leave him for longer than 5-10 mins, and I would NEVER go into a grocery store or Walmart, etc, but I think if a person does leave a dog in the car, in the shade, windows down, on a decent day, I'm not going to flip out about it.