But... OP thought baby had been fed at home and Chick was for Dad?
I have tried to keep up but is it known that they went into Chick or to the drive through?
Cooper could have fallen asleep on the ride, slept through drive through, still asleep when left in the car. Thus still in position at his passing.
If Cooper knew he had been left couldn’t he have wriggled out of the car seat?
There was a case up stream linked about the little boy who got out of his seat and moved around causing the car alarm to go off repeatedly only to have dad click it off from a window.
In this scenario [even though that is a small SUV with the child’s head, albeit in the high sided seat, right there] Dad goes on to work leaves car with other things on his mind and at some point remembers, makes a trip to the car fearing the worst and while approaching sees Cooper in the back.
Dad then acts like he put something in the car to cover his trip and retreats to gather his thoughts.
This is based on OP home experiment of being able to see enough of the child to know it was there through the tinted windows immediately on approaching the vehicle. So if dad was thinking he may be in there he is going to be looking as approaching.
I sometimes go to my car to get something during the work day but can’t recall a time I took something to my car unless I was on my way out anyway.
In this scenario Dad takes some time to process this incident and after seeing Cooper, feeling he was dead, looked it up to see if there was any chance…left as soon as he could taking a few miles to get up the nerve to start the beginning of the scene
I wouldn’t think he was in his right mind were this the case and the search query was only barely veiled.
This is not normal behavior but maybe he was sort of scared of the wife thinking he doesn’t do things correctly and he froze up.
All IMO