That's how the school does it for the safety of the students. They have a drive through with three teachers on duty before and after school. A teacher looks after one of the three cars at the beginning of the line, opens doors, helps kids out and closes doors. Parents stay in the driver's seat with the engine running, then drive off when all the doors are shut. They even have one of the grounds staff at the road entrance directing traffic to ensure safe pedestrian passage on the footpath that crosses the driveway.
Twice now, I've gotten out and opened the tailgate when the teacher was a bit slow (once there was only 2 teachers on duty) and both times was told, "Please stay in your car, the teacher on duty will look after the doors.
It seems to work well and I've never heard a teacher complain.
I was a Deputy Principal in a former life and I understand the pressure on schools to maintain and document a safe environment. They have to do written risk assessments and traffic management plans for student pick up and set down. What this school should do if the teachers are unhappy is to recruit some parent volunteers and train them to do the job.
