A big problem is finding people who know the subject AND have "education major" credentials.
The solution for high-school is obvious. Allow anyone who has taught the subject at the college or community college level for 2 years or more, to teach high school.
It's rather silly to require an "education" degree to teach high school seniors, but not college freshmen.
If you want to teach, say, math, you should be required to get a degree in math. And you should also have to take some education courses. Because those education courses do have value. I've taken them, and while a few were useless, I've benefited from most of them.
The math degree is for the 'what' part of teaching. The ed courses are for 'how' part of teaching. The
A college teacher basically needs to just impart knowledge. He doesn't have to worry much about motivating his students. And it's no big deal if a students washes out of a college course. In fact, that's often a good thing. A pre-med student who washes out of a college chemistry class is just getting a needed wake-up call.
But a good high school teacher needs to both motivate and instruct. And you must try to prevent anyone from washing out. So it's a slightly different situation.