I don't think the main cause has anything to do with Math or Science per se. Someone upthread said that there's a profound anti-intellectual trend in America. I agree, but I think it specifically takes the form of A DISDAIN FOR PROBLEM-SOLVING SKILLS IN ACADEMIC SUBJECTS. This is just as true when it comes to Shakespeare as when it comes to Math.
The life-goal in America seems to be to get a well-paying job in which you don't need to think very much. I doubt this is a conscious goal, and it sounds so insulting that I doubt most people would admit to pursuing it. But in my experience, it is what people pursue -- and our education system trains people for it.
I became very aware of this when I started teaching computer classes. I was teaching applications such as Photoshop, Illustrator and Flash. Most of my students were upper-middle-class, educated, "smart" people. The majority were middle-aged.
Over and over, I heard people say, "I can't do this stuff. I'm just not a computer person." Now to some extent, this is true. These people were born before the Internet and the PC revolution, and their fear of the technology WAS a stumbling block. But the bigger stumbling block seemed to be that these folks couldn't handle basic problem solving.
The apps I taught mostly didn't hold your hand. For instance, if you want to make a photo look a certain way in Photoshop, there generally isn't a button to press. You have to think through the various tools and figure out how to combine them to create the look you want. That said, it's far from rocket science. I found that the moment I stopped giving people a formula that they could learn by rote, their brains turned off. It soon became clear to me that the problem wasn't new technology; the problem was that I was expecting people to use their brains in a way that no one else expected of them.
I started thinking about what these people did all day at their jobs. Gently, I asked some of them about what they did in their jobs. Many of them hand distinguished careers. How could they perform well at work without problem-solving skills? Answer: they don't need problem-solving skills.
It's not always obvious that these people don't solve problems (or puzzles), because many of these people are experts -- meaning that their brains are crammed with obscure facts. Our schools do very well at training people to learn facts*. At least when I went to school, memorization was pushed as a major intellectual virtue. We memorized the multiplication tables; we memorized the periodic tables; we memorized speeches form Shakespeare... Cultural literacy was pushed, too, though not as hard as memorization. No one was expected to really get into Shakespeare, but you were expected to know who he was and to have read one or two of his plays.
(*true, in America shocking number of people can't tell you the name of their congressman or the capital of North Carolina. But these people DO know the facts needed to get their specific jobs done.)
Pop-culture values reinforce fact-based intellectualism. A couple of years ago, if you'd asked people who was the smartest man in America, many would have said "the guy who won all that money on 'Jeopardy.'" (When I was a kid, there were many game shows on that actually required some problem-solving skills. These are almost non-existent. The shows are all about trivia now.) A "smart person" on a drama or sitcom is usually a guy who knows a huge number of facts.
I grew up around (humanities) academics, supposedly the ultimate smart-set. In my experience, they were coasting on memorized facts just as much as people in the corporate world. A professor would read every major German novel written in the 19th Century and all the critical writing about 19th-century German literature. Then he would spend his career passing on facts to his students. His "intellectual" work mostly involved keeping up with academic journals (learning new facts).
(From what I can tell, most G.P. doctors and most lawyers don't have to do much problem solving either. I do know that my doctor seems to be able to make a good living by doing the same formulaic tests over and over.)
Let me be clear that I'm not anti fact or memorization. Facts and rote learning are important. Facts are the building blocks you need. The are the tools you use when you problem solve. Problem solving is the next step. But it's a next step that most people don't take and don't need to take.
I don't think it's laziness. One can get by in our culture without problem-solving, so why bother with it? By get by, I mean that one can make a good living, have a big house, kids, etc. without having to solve intellectual problems.
And -- most important -- one can be a "smart person" (as our culture defines it) without solving problems. Most people want to be smart. They want to be seen as smart by others. Our culture sends a really strong message to them, which is "memorize a lot of facts and you'll be smart." My guess is most people think they ARE doing rigorous problem solving when they see something that needs to be done and have to search through their mental database to find the right fact or the right formula. I guess this IS a kind of problem solving, but it's the easiest kind. It's similar to solving a problem by searching on google until you find the answer.
When I was a kid, there was almost no problem solving in school. How often did the teacher just present us with a puzzle and say, "Here are some tools. Solve the puzzle!"? Almost never. One would think that MOST of education should be about solving puzzles, but in my experience, almost none of it is.
The exceptions (to a point) were Math and Science. But unless you're going into specific fields, you can quit taking Math and Science pretty early on in life. The other courses are easier and it's pretty clear you won't need Math and Science to get by in life. So why waste your time on it?
Meanwhile, the few people who stay in problem-solving fields move further and further from the intellectual norm: I program computers for a living. Which means I solve puzzles eight hours a day. I constantly have to create something from nothing, and I constantly have to learn new skills. Sometimes, I am so mentally exhausted that I can't do my job.
It was when I started discussing this with friends that I realized how different my career was from most of theirs. Sure, they often are exhausted at work. But they CAN get their work done. They say things like, "I was SO sick of filing today" or "Uh. If I have to grade ONE more paper!" But they don't say, "My brain just shut down and I was unable to figure out..."
I know this sounds snobbish. But I am not trying to diss other people or their jobs. My doctor may not do much problem solving, but I am grateful for his help. I am just saying that most jobs involve little or no problem solving. Mathematicians are from Mars.
I have been talking mostly about corporate and academic jobs. In reality, I think there's a lot of problem solving going on in America. It's just outside of the intellectual world. And it follows a long tradition. In America, our main problem solvers are farmers, football players, carpenters, etc. People who build things and who play games MUST solve problems or they fail. It's really weird, because most such people can't talk the intellectual talk. They don't know Shakespeare from Euler. So we don't consider them smart, and they aren't smart in the limited way we tend to define the world.
Meanwhile, the "intellectuals" are barely using their intellects.