I was so surprised when .....

Five of mine have never, ever sent me a 'thank-you' and I think its very rude. One of them does, he's my daughter's child - but none of the others have ever written a single syllable.
I did mention it to one of my sons and he said modern belief is in teaching children to be truthful, and by encouraging them to say how much they enjoyed the (carefully chosen) gifts, even if they hadn't enjoyed them, was teaching them to tell untruths!
When I got over this rudeness I vowed to send money in future. Its not the kids fault after all.
So I now wait 10 days or so then message and ASK if the money had arrived safely.

All four of our grandchildren send me thank you messages for Christmas and birthday presents which I appreciate. They are aged 7, 13, 15 and 19.

We taught our children to always send a thank you card for any presents given to them and they have carried on the tradition with their own children.

We sent out Advent Calendars (no chocolate) to 7 grandchildren and got 6 whatsapps. Wolfie is too young.

he obviously loves you..

That is a lovely surprise to get and I believe thank you emails or letters should always be sent, sadly they are not always.