Gosh I have never had that happen, personally.
But that is really rude.
I would think, most adults, would think about the ramifications of them just deciding they were not coming, at the last minute. That is time and money... and not to mention any goody bag costs, for the Host family.
And especially, in disappointing a child, on their birthday. By not showing up. When they SAID they would.
Really, beyond, rude.
There is no excuse for that. Once a person commits and says they are coming, they should. OR if unforeseen circumstances comes up, then they SHOULD call the Host and tell them they cannot come,
For my kids parties, I send an invitation with my phone number AND e-mail. And an RSVP due date. For attendance or not.
ALWAYS I put a deadline on it. And I specify.... "Johhny and 1 parent is invited.." kind of thing. (to deter people from just bringing too many people to the party who were not invited, and it keeps budget in check). And then I also specify, if it is a drop-off party, or the 1 parent can attend too with their child.
That has always worked, for me.
It really is a disappointing thing, for the Birthday child... when people are so flaky. And no one shows up, who promised they would.
Very very, rude, to say the least.
I also, well my Husband and I, do not ever have kids' Birthday parties, that are that many people. We only invite, THEIR close friends. Never an entire classroom. And only our immediate family, Aunty, Grandma kind of thing.
But regardless of the size of party... people are RUDE, to just not show up, when they said they would.
Unbelievable.