After a conversation with a coworker yesterday, I have to assume that the kids situation is at least in some part due to ignorance.
I mentioned I was going to HOS this weekend, and she got all indignant, saying she would NEVER return for that event. They took their young child last year, and, predictably had the bejesus scared out of her, which she thought was unacceptable. I said, well, that's the whole point of the event, they make it very clear that after 6:00, it's not a kid friendly event. She countered by saying they had been near the tea cups, which she considered a kid ride. I explained (in a nice way, we're friends) that a) it's not a kiddie ride, b) there is an entire kiddie section of the park and, most importantly, c) there is a scare zone RIGHT THERE. She finally conceded that she had paid no attention to the event info, didn't know there was a difference between day and night ops, what time the event started, or that there even were scare zones. She assumed it would be regular park operations with Halloween decorations.
I'm definitely not saying that's the reason MOST families with kids are in the park, but it must be true for some of them.