Agreed. We waited the full 15 minutes on trust, but having driven there I would have preferred to sit in the car. If people are planning to drive it might be an idea to do that anyway - no delay to others, and avoiding getting into difficulty while driving?
Had my booster (Moderna) at a grocery store pharmacy in Texas and they never mentioned any need to wait. I was in and out in just a few minutes.
That sounds like a liability for said pharmacy. Got mine at the Kaiser yesterday and they had signs up all over the place.