Children these days have different attitudes for many reasons, but I believe that inadaquate supervision is at the heart of it. When Dad worked and Mom stayed home and took care of the kids, children were better behaved. Now, they get away with more, and harried parents just do the best they can, which often isn't enough. Children are unhappier. Bullying and abuse is now commonplace. It's not easy being a kid anymore.
And society doesn't help. Look at the movies, shows, music and games kids are exposed to. School has gotten harder, money has gotten tighter, prices have risen, and more kids need to work outside of school to earn spending money. Our generation did too, but school wasn't as difficult then. And children from higher socio-economic status just have different sorts of demands placed on them.
To teach kids respect they need good models of respect and know how it feels to be respected. I live in a town where children say Ma'am and Sir, Miss and Mister, because that is what they are taught from a young age and that's how they see others speak.