Waiting in the parking lot for school to get out and the kids to find their parents' cars is one of those writer's opportunties to observe character.
For example, someone's just gotten out of her car and into the station wagon she's just parked next to. She's got her gloves in one hand and a sheaf of papers in front of her as she speaks to the wagon's driver (I can't see if the other driver is a man or a woman).
Another woman gets out of a van across the lot and arranging small rolling airline baggage in the back, and walks over to a small hatchback. She and the hatchback's driver, another woman, arrange a spare tire in the back of the hatchback and the two of them wrestle the luggage into place.
In a Toyota, slowly cooling as heat seats out through the floorboards, a bored dad is rocking out to ABBA's "Take a Chance" while he types up the activities of the parking lot -- his fingers flying over the iPad's touch screen. If this were a story he'd be the detective, and the other parents would be smugglers, spies, or secret lovers. The papers would be government plans or private coorospondence; the luggage would hold supplies for refugees to be delivered to a safe house.
Ah, the kids come running across the street and into the parking lot. We all go home.
Now... how to turn this into a short story.