Is it too late to learn manners?

Okay, if I can go back to school to take class, exams, write papers, and even become someone else's graduate assistant, can't other people in the grocery store check-out line learn to behave and be polite?

I had to help the check-out gal bag my items because the people behind me were so rude and impolite (oh, yeah, and because Kroger will not employ enough people to help her!). My son went to grab one more thing while I was bagging and the check-out gal was doing her thing, and they would not let him through--he's only 8--poor guy. So, I'm trying to figure out, does Kroger attract rude people or does grocery shopping just put people in a bad mood?

And people wonder why I hate grocery shopping...