i have a neighbor who complains that she only gets bills in the mail--no private correspondences. and yet she sends letters, thank yous and answers surveys all the time. she says it's just no one understands courtesy any more.
think of all the times you have never answered emails, phone calls or text messages. society is so adept at "getting." we have been trained to receive and not to give. or give back. we expect. having no patience to extend ourselves beyond our own limitations.
i don't think courtesy is gone, but it is surely dwindling. today make it a point to reply, to give feedback, to answer the questions that have gone unanswered because you were busy, or just didn't like the person sending it.