Why is the general public so scientifically illiterate?

There are many crackpots and people fall for them because of their scientific illiteracy. Especially when it comes to Physics, people have absolutely no knowledge of even the most basic concepts. This is why I keep hearing people making crackpot comments about experimentally tested theories such as Relativity and Quantum Mechanics. Why don't people pick up a book and learn something? Are most people idiots?