On our junior daughter's recent birthday, my wife and I ordered an L-size pizza and ate an expensive cake, with our second daughter absent.
She found the receipts and got angry.
However, I think 'it is your (second daughter's) fault for spending time with her college friends and being away from home on the day.
-----
'Why have a party where the person onself is not present?' I would argue as follows.
"Then why are you guys having a Christmas party?"
That person has been dead for more than 2000 years now and is currently absent (if he had been resurrected, he would have died).
However, the birthday events continue and continue.
Moreover, he is celebrated not on the "day" of the birthday, but on the "day before the birthday(eve)", which makes no sense at all.
As I have said many times, his birthday is December 25th, and the 24th is a normal, totally unrelated day.
-----
Our couple's style, to celebrate the birth of the person on the person's birthday, is
"far more sincere than the man and woman who walk the streets on Christmas Eve with the appearance of a couple for anyone"
I believe it.