Because we're paying glorified babysitters and calling them teachers (exceptions exist obviously). They've gone to school to 'teach' but aren't always subject matter experts. (speaking about the US, nearly every other country has subject matter experts teaching secondary school) There is too much focus on soft-subjects in the Education Schools in the US. IMO this is one stark difference between the US and other countries and something that needs to change if we want to become competitive in the pre-college realm again for education.Maybe we could start by paying (public school ) teachers a decent salary? It seems too much to ask of someone to suffer thru 10+ years to get a PHD only to be paid a misery as a high school teacher, not to mention that there is little prestige associated with the position. But then why do we pay athletes, entertainers millions , but skimp on teachers' pay?
Out of the many friends that I have whom are now primary school teachers - not a single one of them was 'good' at science/math when they were in school. They begrudged every little science or math class they had to take in college, and I'm sure that attitude isn't helping them or their young impressionable students at all. Also, I have a pair of friends whom went to school for math (getting a BS Math) and then became high school teachers in a certification program - they have both quit for significantly better paying jobs. Imagine if we could actually pay subject matter experts what they're worth?
Unfortunately with teacher pay currently, they're probably getting paid what they're worth - there is no outside competition for someone with a 'teaching degree' but there is other competition for someone with a degree in a subject (esspecially a science/math degree). So, how do you draw subject matter experts from other competitive jobs to teaching without overpaying the not-qualified-for-anything-else teachers? Some states do have a bounty for certain subjects (math generally), and even some states have a 'quick-track' for STEM secondary teaching certificates (2 states I know of have 2 semester M.Ed. programs - 1 semester of classwork and 1 semester of student teaching, prerequisite is an appropriate science degree). This isn't enough though, since the guarantee of better pay still isn't there. Why would someone spend an extra year in school (to get the M.Ed.) when they could get paid more from going into industry (And less debt)?
I don't think there's an issue of religious indoctrination occuring except for that it's filling a void caused by a lack of properly qualified teachers. Everyone can probably remember teachers from their childhood whom were good (and there are some very good teachers out there), but then there's also the teachers that even as students you knew they were there because they had no other skills.