I’m guessing it’s because the perception of people who don’t have kids have the thought “every time I’m in a restaurant I see kids on their parents phone/ipad so that must be what they do 24/7”, and I’m totally guilty of that too. Once I had a kid, I think me and my partner had a pretty good no screen time rule but when we wanted to go out to eat at a restaurant that rule was relaxed not just for us but for everyone else as well.