Some adults can be pretty badly behaved too. Just look at the number of adults who get drunk on planes, at football matches, in pubs and restaurants, etc., and cause mayhem
Surely, if children are running around, touching things they shouldn't or being excessively noisy, their parents should be asked to control them if they wish to stay but I don't see why all children should be banished.
I get the point that there are plenty of establishments that welcome children (and I agree there are too many parents who let their children run riot). However, I don't really like the idea of a blanket ban on people on the grounds of their age.
I have heard similar sentiments expressed by working people complaining about retired people making a nuisance of themselves by going to the bank, shops, post office, etc. etc. during the "lunch hour" when they should apparently make themselves scarce.