Engram wrote:

Am I being unreasonable in thinking that a kid turning 7 years old would be
expected to say "thank you"? I'm not asking for a great outpouring of
emotion and exclamations of "you got me my heart's desire and I will love
you forever for this" or for her to go dancing around the room pronouncing
my greatness. I just kind of thought she'd say "thank you"... At what age do
kids normally learn the social norm of thanking people for gifts?

Well, you already know the answer to that question.
Of course it was rude. Seven year olds are sometimes
uncivilized, so one makes some allowances, but at the very
least a parent should have been on hand to prompt her for
some more acceptable behavior.

Best wishes,
Ericka