As an avid card maker and sender, the daughter and d-i-l of teachers, the m-i-l of two teachers AND the author of two books (obviously I like to write) I feel led to add my few cents here.
1) Young people today generally do not send cards and letters. I've observed that they DO seem to appreciate receiving cards and letters even more than the previous generation - but they really don't know enough to repsond.
2) I will continue to send them (and anyone who needs a word of encouragement) cards and letters because it is my way of lifting up a generally down trodden world.
3) The problem with our our generation is that we give expecting to receive something back. That is not what we should be doing. Someone in a previous post mentioned setting an example. Sending small or encouraging gifts and notes should be done simply because WE want to encourage or help someone else.
4) Should others send thank you notes? Of course they should - but because they don't know better, we should NOT stop us from doing what is right. Maybe just a gentle nudge (Wondering if you received my gift?) will let them know that you would like an acknowledgement of receipt (not necessarily a gushing thank you). Certainly if you send money in the mail the person should at least send something back (even an email or a text) saying they received it.
5) Our generation wrote letters. The next generation writes texts, tweets, FB posts, etc (btw - even emails are old hat now). So long as they keep in touch with me - I don't care what they use to do it. Maybe that's why my sons, dil's and so many of my neices, nephews keep in touch with me so often when others "never hear from them".
5) Lastly - I have a friend that every time I send her a card, she feels she must send me a card back thanking me for the card. Then I feel like I should thank her for the thank you. Where does that stop. I always tell people that I do what I do (sending cards for no reason) just to lift their day and encourage them. I expect nothing in return. That way there are never any hard feelings.
OK... so I've added my thoughts to the pot. Not all of us will agree, but I'm very appreciative that this forum exists and that we can share our thoughts.