Actually, I think you're giving them way too much credit. Kids today understand nothing. They have absolutely no sense of historical awareness. They really and truly don't know anything about the world in which they live. What's more, most of them have no interest in knowing.
I suspect that most of the people on this list are Baby Boomers and did not have the experience of attending public primary and secondary schools in the late 70s and 80s. Public schools in this country -- and in California particularly -- rank somewhere between bad and useless. Most kids who graduate high school are barely literate, and many of those who go on to college are scarcely better off.
Some random examples: I remember being shocked when I was in junior high (c 1986) that a good portion of the people in my class did not yet understand the difference between a city, state, country, and continent. In a high school history class I was in, only about 5 of us could name the major combatants of World War 2. I recall that one girl (who was white and upper middle class) gave "Toyko" as her answer. Most recently I was in a review session for an upper division history class at UC Berkeley, and one girl who was a senior actually did not know that the Japanese had bombed Pearl Harbor. BTW, this individual was recruited by JP Morgan and is now working on Wall St helping to manage your money. I fear her case is not at all exceptional.
I think there is no simple answer for why this is so. I do not think it can be explained as simply a manifestation of class oppression, because this appears to be a generational phenomenon, cutting across class boundaries. An easy target for blame is their parents, i.e. the entire Baby Boomer generation, who with all their hippy turned yuppy self-absorbed hedonism didn't bother to teach their kids a damn thing (yes, I'm well aware that I'm generalizing.) Another factor I think (and I'm sure this will piss some of you off and you'll say I sound like Allan Bloom) is 1960s cultural paradigm shift, aka the "counterculture." Whatever it meant to you 30 years ago, its real and lasting effect has been the complete breakdown of traditional notions of responsibility, self discipline, and morality. What I mean is the "do you own thing" of the 60s has evolved into the "I'm going to do whatever I want and I don't care what happens to anybody else" mentality of the 80s & 90s. Kids no longer read for pleasure or knowledge because it takes too much self discipline when it's so much easier to engage in the "revolutionary anti-authoritarian" act of smoking pot and watching MTV. Traditional notions of morality have been brushed aside in favor of an extreme relativism which excuses any act i.e. "Well, who are you to say that it's 'wrong' to kill 500,000 Iraqi children. It's only 'wrong' to you, but it's 'right' to someone else, so don't try to impose your morals on me!" (an excerpt of an actual discussion with a "liberal" Gen Xer.) Another factor is of course the dumbing down of the population across the board over the last few decades. The transformation of the US into a "post-industrial" economy over the last 25-30 years has eliminated the need for a skilled workforce. Now we just need a few educated people to work in the information sector, and the rest can flip hamburgers or go to prison.
Additionally, college is no longer associated with the pursuit of knowledge or the love of truth. It is now EXPECTED that all kids go to college, as it used to be expected that all kids go to high school. It's not something young people do because they have an intellectual interest, it's something they do because it's expected of them or because they realize they must have a degree in order to make money. In such an environment, intellectual curiosity has little chance of developing.
Forgive me if I'm rambling. I'm a Gen X undergraduate myself, I work 2 jobs, and I'm exhausted.