That's a very good point. However, I think even an english/history/math/whatever teacher could make a decent computer science teacher with the proper training.

That's a very good point. However, I think even an english/history/math/whatever teacher could make a decent computer science teacher with the proper training. "Learn Java in 4 Weeks" is emphatically not the proper training. You're absolutely right, and it's a shame that no one is willing to invest in computer science education.