This sounds like maybe something that school has implemented, as well.
When I was driving school bus there was a kindergartener who's mother picked him up part of the time. I was never informed when she was and when she wasn't. One day his father chased down my bus, he's an arrogant fellow anyway and now he is scared, too.
Anyway, the boy had gotten on the wrong bus without Opal seeing him and had ridden that bus on a 40 mile around trip back to the school. No cell phones back then and Opal did not see him in the back until she was headed back to the school. His parents were terrified, we all were. After that Kathleen came and told me when she was taking him.