No offense, but do you expect children to behave perfectly, all of the time? Especially with bad examples?
How can we expect that of children when even adults don't know how to comport themselves properly half the time? (Paris Hilton, Vince Neil are two that come to mind immediately for me). Heck, my husband sees people come into his restaurant that don't behave half as well as our children, and these people are adults! :0)
Of course I've seen really well-behaved children and attentive parents at times too, but there seem to be fewer of them than the other kind. I live in a blue state, so maybe that makes a difference.
And yeah, no doubt there are tons of ill-mannered grown people out there too. But I figure when parents have kids in tow they should at least make a good effort to keep them behaved/out of the way (just common sense), etc.