Well, thanks for the opinion on my 12 year old self.
I'll tell the rest of what I left out.

My friend asked me personally after I heard her and her mother discuss that apparently I had been overlooked and wasn't invited because I didn't live in the 'right part of town'. Since her mother had met me and found me to be polite and not dirty, smelly, and rude, it was then decided that if the daughter asked me and I wanted to go, the mother would then get me an invitation.
My first year at the school, I was also not invited.
It wasn't quite as simple as my first explanation, but I wrongly felt I didn't need to go into every single detail.
I was already attending functions at that same level of society since I was much younger, and I managed to learn which fork to use and how to carry on a proper conversation without the program. I learned to dance in my dance class, as well. (So, yes, as a child who was already doing those things, I found it humorous - and slightly degrading - that my friend's mother was worried about going out on a limb because I did not live in their part of town.)
I wasn't saying that it isn't a worthwhile program overall - I'm sure for those it suits it is. Where I live, it *is* just for those special snowflakes who happen to be born to rich parents and live in the appropriate part of town. (Since, you know, the other 80% of the children in the city will never be in a situation where they will need to know the same things!)
However, it is not the only way to learn the basics of functioning in (high) society. It is not worth 'forcing' a child to attend. And that is the only point I was trying to make.