Gotta agree with OTF -- it's not one particular generation or age of people. It's mostly how you're raised and how you think. Some folks just didn't have the advantage of growing up with parents that taught them courtesy and concern or respect for others.
That stuff was drilled into my head from an early age -- open the door for ladies, stand when a lady enters the room, a firm handshake when you meet/greet someone, don't interrupt when someone else is talking, let others go first, never use a toothpick in public, napkin in lap, elbows off the table, don't talk with your mouth full, don't slurp. OK -- those last few are possibly off topic, but I wanted to give a nod to my Mom because she's probably watching right now.
My folks didn't teach me to load my sparkly bass boat before I backed her into the lake, not to cut between a fisherman and the bank, or not to throw a wake where it will affect others. They didn't have to.