I think a lot of these rudeness issues evolve more and more as we get more and more into the entitlement era. These people have rights and they're going to exercise their rights to do whatever whenever and wherever they want to. Too many people today seem to forget that their 'rights' often infringe upon the rights of others, but they don't care, because 'their' right supersedes all other rights.
They want to run into the store and get just a few items and all the parking spaces are filled except for three handicapped slots. Their time is more valuable to them (and they're lazier) , so what's going to hurt, after all, they're not taking up all the handicapped spots, there are still two open, just in case, so they're not hurting anything. If they want to block an aisle to chew the fat with their cousin, well, they've got a right to talk with their cousin, and you can always move over an aisle, then come back down to get what you want, they're not really hurting anything, so who cares?
If they need to go to the store and they're still wearing their PJs, who cares, they've got a right to go to the store and get what they want, you don't have a right that says they need to at least put some decent clothing on first, so they're exercising a right and you have no rights to stop it, or even dislike it. Their rights are always more of a right than yours. If they want to eat in a restaurant with their hat on, well, there's no law that says they can't, and they have a right to wear a hat and a right to eat, so what's to stop them?
They could care less for what you or others think of them, they're exercising their rights and you're just expressing your opinion. Which is more important, a right or an opinion? To them, their rights are the most important thing to protect, to others like us, courtesy, consideration of others and politeness mean something.
When I was in law enforcement, I got so tired of hearing that kind of stuff. It seemed that almost every time you went on a non emergency call, at some point during the conversation, someone, or two, or three would remind me that they had a right to do this or that, so what was the problem?