I had an extreme experience with this kind of policy one time. When I was 19, I accompanied my parents on a 2-week Alaskan cruise on World Explorer Cruises (an education/ecology focused line, not a luxury line). As occupants of a fancier stateroom class, we were invited to sit at the captain's table in the dining room one night. A few hours before the dinner, we were given a letter explaining they had not realized my age, that the captain's table did not allow any guests under the age of 21, and that while my parents were welcome, "Ivyspice is invited to eat with staff member Lisa."

My parents refused the invitation, explaining that they didn't trust "staff member Lisa" to tie on my bib and cut up my fish sticks. So the three of us sat at our usual table. I thought that that was carrying the "no children" rule a little too far.