Now I'm probably gonna piss someone off but here goes...
I think there are a lot of contributing factors to how we got here, but one of the biggies imo is that we stopped properly disciplining children. I almost can't stand going shopping because I know I'll encounter a bratty child telling his/her parent what to do, and the parent is catering to the child's whim. "ok you can have some candy" or "stop crying and we'll go get some ice cream" or the worst, the child is running up and down the grocery store aisle pushing one of those kiddie carts and running into people and the parent is oblivious. I had this happen to me and I turned around and said loudly "EXCUSE ME?" which got mom riled up - she thought I should have kept my mouth shut because it was "just an accident - he didn't mean to run into you". She missed the point - I wasn't really upset with the kid, I was upset with mom.
When we stopped spanking (not beating - big difference!), or at least sternly disciplining children, and making them behave in public places, many kids turned into holy terrors. I spanked my daughter, but I can probably count the spankings she got on my fingers with one or two left over. I saved the spankings for the BIG lessons - like when I caught her playing in the road. But because I said what I meant, and meant what I said, I didn't have to spank often - she usually did what she was taught.
"Stop that or you're going to your room... 1... 2.. 2 and a half... please stop... I'm going to tell your father..." -- threats with no follow through, I hear this one a lot too. Your child doesn't believe anything you say, doesn't trust you, and will constantly try to push your limits to see where they are. I actually feel sorry for these kids.
Just like a baby feels more secure when they're swaddled up snugly, a child feels more secure when s/he knows his boundaries and are taught to be responsible for their actions. These kids that rule their parents, and aren't taught to be responsible for their actions, are the ones who are seriously messed up by the time they're adults.
Edit : Well, THAT was off topic - sorry! LOL But the grocery cart thing was recent and was still on my mind so I guess I had to vent.
Completely, 100% agree! We rarely had to actually "spank" our son -- thanks to two spankings he got at the ages of 4 and 5, when we were literally at the end of our rope with just exactly WHAT to do with the boy -- 3 licks with a belt on his fanny drove the point home to such an extent that forever after, all we had to say was: "do I need to get the belt?" and he was INSTANT compliance! Naturally we tried other measures before resorting to the belt -- we're not monsters or child abusers! -- and they were ineffective; but that belt served as a deterrent for the rest of his growing-up years.
Once, in a store, when he was about 9-ish, he was just pitching a FIT for some trifling item that we truly could not afford -- I mean REALLY pitching a fit -- so my husband smacked him and said "you're hysterical, snap out of it!" Some people at the end of the aisle looked his way, and he just stared them down. They went their way without saying a word.

About a year later, some boy in our neighborhood had done something really awful to our son, so the whole family walked up to their home and confronted the boy and his mother about it; she demanded that he apologize, and the boy flatly refused; her response was "just wait till your father gets home." On the way back home, our son commented that he couldn't believe the kid had just flatly refused an order like that; I asked him what he thought might happen if he did that, with us. He said there was no "might" about it, he'd certainly be picking himself up off the ground. I said well maybe not off the ground, but that was a good estimation -- then I asked him if he'd ever heard me say 'just wait till your father gets home' about anything to do with his behavior -- he looked at me like I was crazy and said it never occurred to him that I would EVER say a thing like that! I was MAMA and he did what I said, or faced the unpleasant consequences! (in fact sometimes his father getting home was a relief, as dad would let him out of his room, with orders not to piss me off any further or he'd be going back in!)
When he graduated, there was some conversation about the insanity of someone's parents at the graduation, and he gave us the highest compliment I think I've ever received -- he said we were the SANEST parents he'd ever heard of or encountered! Considering US... well, that's something I really never expected.

Now, he's almost 27, and he's a wonderful person; truly one of the funniest people I've ever had the pleasure of knowing -- and he seems to actually LIKE us!
But the hardest part of being a parent, other than one's kids being sick, is having to sometimes be the "bad guy" -- but if you don't put the hammer down on bad behavior or go investigate the poor grades personally, then the child becomes a "bad guy". I think most parents nowadays don't have any idea how to do that -- and it shows.
Andria