It doesn’t say, but as a parent of five kids, I’m going to bet the 2 year old fell asleep and dad didn’t want to wake her. Maybe I’m being too generous, but I guess I’d need more information to be so certain about judging them.
I’ve probably done shit like this before although I’d never let the car out of my sight. And certainly not in 111 degrees. A/C doesn’t really work that well when the car isn’t in motion.