I either send a short thank you letter or I may send an email especially if something has been sent by post and these days one does not know if the item will arrive. This is especially where I live, we receive mail from the PO and 10 minutes later something else from TNT, that is if it has not been dumped in a bag behind a bush.
I think that it is common courtesy and politeness.
Live screening of an execution and send ups of the death of a mentally ill man in a tiger compound
) when we have gone to the trouble of making a lovely meal for someone and we don't hear from them afterwards - so would never do it to anyone else.