The Weird Rise of Child-Free Events

I come from a large family. My nuclear family is only five, and my father's side was another eight (while I was growing up). My mother's side is now topping sixty people (it was closer to 45-50 when I was young), and the bulk of those are my cousins.  I'm used to events having a large number of children present, and wouldn't know what to do with myself if there weren't a whole herd of littles underfoot during pretty much every family event.

Recently, however, it's started becoming more and more popular for people to have events that come with the notation "adults-only," or "please leave your little ones at home." This is actually distressing, and for several reasons.
First, there's the very specific reason.  Generally, if I'm going to an event, I'm coming in from out of the country to attend. Not just out of town, mind. And not a half hour to an hour drive. I'm usually traveling 8+ hours by car, Mad Natter in tow, to attend family events. Where, pray tell, does one find a sitter when you're eight hours from home and all your family is at the event in question?

Second, family is family. Why would someone not be welcome one week, but welcome the next - and the only thing in between the two dates is their birthday?  Why is it that children are seen as lesser members of a family? Why is it okay to deliberately leave them out, when it's incredibly gauche to have a party for family, but ask that this specific Aunt/Uncle/Cousin/Child and their branch of the family not attend?

Third, I am a mother. That is a large part of my identity. Having a child with special needs makes that a larger part of my identity than it might be for other mothers, as it takes up a whole lot of extra time and attention. I enjoy the company of my child, even if he does occasionally drive me nuts (don't all children make their parents crazy from time to time?). Why on Earth would I want to attend an event where he is unwelcome simply because of his age?

I am, as I've said before, a gifted adult. I am intense, I have a huge amount of focus to use to my advantage, and I have a gifted child. He is also intense, and he is sensitive. If I'm going to these events and manage to find someone to care for him while we're five hundred miles from home, he knows something is up.  It doesn't hurt that he can read quite capably, and even at six, understands what "no children" means, and while he doesn't understand why someone would say such a thing, he does understand that there is a party going on, and he is not only not "cool enough" to attend, but he knows the majority of the people at that party, but is still unwelcome.

I absolutely cannot comprehend why it is that someone would say "Oh, I'd like you to come to a party and bring gifts... but please leave this specific member of your family at home."  I understand in the event of things that are distinctly child-unfriendly, but if your event is neither being held in a tea room, nor a burlesque club, why is the child unwelcome? And once it means ruling out your own children or grandchildren, will that "no children" policy still stand?

There is actually very little in this world that makes me feel less welcome, or more belligerent, than being told that I may be a mother, but I must leave that aspect of my self at home in order to attend an event... which is, for most of these events, an event honoring a specific person (or people), and in which I am expected to not only spend money to travel to be in attendance, but also to bring a gift... AND to hire a caretaker for my child, who will be far from home, and likely not even casually knowing the person who will be minding him for the night - and let's not even go into how big a hardship that is, both for him and for the caretaker. There is no good reason children are not welcome. It is simply people who just don't like children making unilateral decisions... which is extra-bonus-fun when the event in question is a baby shower.