Personally I hate thank you cards, emails, etc. Cos the cards go in the bin. I may not see an email for a couple of days so will get texts asking if I have seen the email. I end up replying to texts which can sometimes turn out to be a few texts to one person. I don't like phone thank yous because it ends up talking shite to a kid.
If I give a gift, them saying thank you there and then is enough. If it's someone abroad then a text to say they got it and a quick thank you is fine. But I've nieces and nephews who thank me in person, then they get home and I get a text, then a few days later I'll get a card. It's ott and no need for it.
Lots of people expect written thanks, some even like more than one thanks, dhs family are big into written thank yous, they actually pass the phone around them all saying thanks and what they'll do with the money or how they've always wanted this toy etc, the calls can last for up to an hour, then they always do a written card, I got 12 this year just after Christmas, they all went in the bin. It's a waste of time energy and money doing this.
My own kids thank people there and then if it's from abroad they'll pop a quick text, if too young to text I send one to say it arrived and thank you. If people don't like that then unfortunately we're not going to change, so might even work out and people send less presents.