The breakdown of the family unit (arguably due in large part to latchkey kids) began the decline in academics in the U.S.. As standards of living rose, two income families became the norm. Kids don't just willingly do homework/study. They must be urged to do so.
At the lower end of the spectrum, we have third and fourth generation illiteracy in the inner cities. There might be value placed on education in some homes, but the parents couldn't help the kids with studies if they wanted to.
The Asian cultures don't seem to have those issues. Granted, their kids might suffer more stress as over achievers, but there's a balance somewhere.