The person waiting in the car is still spending time on the errand.

Waiting is work, even when it produces nothing visible. The passenger who stays with the car, the parent circling the block, the friend holding a place in a queue: none of them appear in the story of the errand, yet the hour left their day the same way it left yours. Household effort gets counted by activity, so the still parts of it tend to vanish from the ledger.

When you next divide a shared task, count the waiting alongside the doing. Thanking someone for time they spent sitting still is a small correction that people notice.