How rude!

Anyone who has ever watched the show Full House remembers when one of the little girls used to say "how rude"!  Well....I wanted to say that today.  We were out shopping for groceries at BJ's and when we were done we got in line....the line next to us opened up and we hopped in it.  We saw this couple who just had a few items and we told them to go in front of us.  So they went in front of us but never...never...never even said thanks...or gave us a head nod....nothing.  Why...why are people so rude that they cannot even acknowledge with a common courtesy.  I would not be so upset if I did not believe that this is becoming the norm and not the exception.  I seem to see this more and more and it bothers me!  We need to get back to the days of Good Morning, Good Afternoon, Good Evening, Hello..how are you, Please, Thank You, Nice day today, ....etc., you get the picture.  Don't you agree?