Kids break curfew despite being home and inside the house

I have a family where both parents have Get to Work Jobs and I usually follow one of them to work everyday. The dad is a scientist and finishes at... 8pm I think? And with parenthood I have the kids' curfew set to 9pm. If the dad doesn't fill up the performance bar in time I make him stay an hour later meaning he comes home at 9pm. So when he comes home at 9pm, all of the kids suddenly take a hit to their responsibility level and the parents have the option to discipline them all for "breaking curfew" despite them being home and inside the house.

Why is this a thing that happens?