I agree that YABU.
As for people giving charity donations, I have heard a number of people saying that they doubt that it is the case, as if it is somehow cheating. There is no real reason why we should spend £££ on buying writing and posting cards. The 'custom' was invented to make profit for the manufacturers, so choosing not to line their pockets doesn't oblige anyone to make a donation or buy something 'worthy' instead, and to expect a relative to buy a particularly expensive card is just ridiculous, I think.
I stopped sending cards years ago, other than to my mum, my MIL and a couple of other older people who would be upset if I didn't. I don't pretend that I am making a donation to anything (I do that all year round with no announcements), I just tell people that cards are not 'my thing' if I'm asked, which I rarely am.
These days, people don't need to send cards to keep in touch in the way that they used to, as they can do that on Facebook etc.