Leaving your children in a car?

[P•Mom]

I am fortunate enough to live in an area where these scenarios aren't much of a problem. The pharmacy has a drive-thru, I go to self-serve gas stations where I am right next to the car fueling and paying on my own, the ATM has a drive-up window. If I need to run an errand, I either leave the child(ren) at home with their father, or I haul them into the store.
I think it's fine for an older child (let's say 10+) to sit alone in a parked/locked vehicle for a few minutes while someone runs a quick errand. An infant not so much.