Incidents like this are common where I live, and we only occasionally hit 90 degrees. Doesn't really have to be all that hot. Just leave the car out in the sun with the windows closed, and before long, your child or pet perishes.
Not long after the casino opened in Pittsburgh, there was a case of a guy leaving his kids in the car while he went inside to gamble. Luckily, someone spotted the kids, got casino security to break them out, then the police were called and the idiot father was arrested. Of course, the anti-gaming crowd pointed to the incident as another reason not to have casinos. Sorry, but casinos don't make people stupid parents. They would be stupid even without a casino.