I assume they've had problems with children not being under control.
I also assume that when challenged some very entitled parents have tried to claim that their own children should be exempt from that rule because they are different, can behave etc, when they're clearly blind to how bad their children's behaviour actually is.
Unfortunately these days there are a lot of awful parents who can't keep their children under control in public places, or more likely can't be bothered to, especially because looking at their phone seems to be more important than looking after children. Also because they believe that their children should have free rein to do whatever they like, irrespective of whether it inconveniences or irritates other people.