My poor dc obviously have an old fashioned dragon for a mother. Apart from when presents are received and opened in the presence of the giver (like pp) they each write letters. ds - 6- writes them himself, ds - 4 - writes who it is to, and the love froms, and dictates the middle bit for me to write, and I do dd - 1 - for her. They're not long, or fancy, just an acknowledgment that someone has thought of them and chosen something specifically for them.
As for not remembering who gave what, we write a list as we go along. Frankly I would be rather disgusted if my children thought Christmas was just a frenzy of present opening without giving any thought to the giver.
We send many presents. My sil has not acknowledged the arrival of her dc's presents. We don't know if they arrived.
Another friend says he just chucks cheques from his godmother in the bin as they're not even worth the bother of going to the bank to pay in. I hope she realises they are not cashed and stops sending them.
Having ranted, I have no objection to phone calls, emails etc as thanks, but something is polite. So, yes, old fashioned, and proud of it!