Saying please and thank you is something we are taught as children, and we teach our children, yet as adults so few demonstrate anything close to good manners.

Although this isn't really related to what you're saying, one thing that annoys me is when people are overly, immensely rude to a cashier (black Friday is the worst). I've never been a cashier or worked Black Friday, but wtf is wrong with people that because you had to wait in line, or bc ur tired, or whatever it is, gives you the right to be so rude to the cashier. I always feel so bad for them and apologize to them for having to put up with such people