While it's tough to criticize the decision to leave a child in the car for a few minutes -- happened to me all the time as a child -- I'm forever scarred by seeing a dead child pulled out of a car in the office complex next to mine [1]. The dad was bashing his head against a tree trying to knock himself unconscious because he was so overcome with grief. Officers were trying to restrain him when his wife showed up and…
As with lots of things: The details matter. Leaving a kid in a car shouldn't be an offense. Not returning ~soon~ might be and might be a reason to call the cops/force the car open. Parents can damage/kill their kids in uncountable ways. Most don't and really try to avoid that. Trying to watch over their shoulder isn't 'Good citizenship', it's crazy and a witch hunt. You start to be labeled as child abuser if your kid…
The second half of your premise contains two completely unwarranted assumptions. How exactly were the police supposed to know the now-departed child was a) safe and b) with his parent? Recall that the Mom who wrote the piece was driving a vehicle that wasn't registered to her and so therefore didn't match the description on the registered owners' driving licenses. We know with hindsight that she had borrowed her parents' minivan for the trip, but the police would not have been justified in making that inference.