I've been to a couple of places where kids weren't allowed in the evening & reason given was due to alcohol being served.

I was in Vienna in June & one of the properties I stayed at had a nice lounge. Staff there was good as well. There was a group of Brits there on bizness who basically used the lounge as their 'pub' each night. They were quite noisy one night (and this was early; maybe 6-7pm). I finally stopped by their table & said I appreciate that you all know each other & are having a good time, but those of us only a few tables away literally can't hear each other because your voices carry & are a bit loud. Perhaps you could lower them just a bit? One said to me a bit belligerantly, is it a problem? I said your being happy is not, but when your happiness intrudes on all the other guests in the lounge so that they can't enjoy it, then yes it's a problem. They quieted down after that. I would have gotten the attendant to say something, but she was in the back room getting additional food. FWIW - this particular property had a good food/booze offering & from what I can tell, the Brits scarfed up both in massive quantities every evening. But the lounge had 3 rooms & at least they moved to the farthest the rest of the time I was there. I would have loved to have seen their expense reports to see if the put food/booze on them. Seems like the type of thing this group would do, even though they weren't spending anything on f/b in the evenings.

BTW - I was chatting w/ an attendant last year at a European property I stay at every year on business in September. She said the staff was thankful that the summer was over, because all the elites bring their families on holiday & the lounge is overrun with kids, and it was nice to have it back to biz travelers again.

As noted on this thread, sometimes parents subjugate their parental responsibilities & let their kids run wild, whereas others teach the kids proper manners/how to behave in lounges.

Cheers.