I find the takes on this very interesting. I have always flatly refused to let anyone in early when I worked retail. It's a bit different at the middle school where I work. We actually had to have an assembly for parents with security and district reps explaining why they can't drop their kids off at 6 am even though the school opens at 6:45.
It began as just a couple of minutes early then the kids began to appear earlier and earlier. Oh, the drama that was had when the building engineer wasn't on time and some kids were left outside unattended in the dark and cold from about 6 until teachers started to arrive at about 6:35. We should be there for the children! Apparently we live at school and are there all the time
I have also had many a parent show up hours after tutoring ends with no apology or explanation. I had a student that I had to remove from my after school tutoring program because even though the parents had been warned about not being there when tutoring let out, they still would show up an hour or more late. One night I was there until 7 pm waiting for parents who would be there in "just a minute" since 4 pm.