No one is good teaching year 1. But those that come out of degree programs have at least been exposed to the things I mentioned and statistically stay in the profession at a higher % than those that come in on emergency certifications. But everyone should have some classwork in things like classroom management, special education law (trust me you don't want to walk into a classroom without this unless you want to risk losing everything you own) and a myriad of other things.
My mentee last year had a degree in the field he taught in and zero background in education. No classes or anything. Kids ran rough shot over him (upper level high school science). The kids that wanted to learn did. The ones who sort of did or didn't never learned anything. Anyone can teach the kids that want to learn. You get schooling in education to learn how to manage the ones that don't.
It's freaking hard to teach. I encourage anyone on here to take a few days per year and visit your child's school and stay all day. Try for multiple days in a row if you can to get some continuity day to day. Don't go in your kids classroom all day either. Move around to different subjects and levels. There's a reason they make degrees for this stuff. Most everyone thinks they can teach until that classroom door closes and no one runs in to save you every time you have a kid that doesn't feel like doing anything. Welcome to every teacher every class every day.
50% of the teaching field is leaving between years 0-5. 50%. Tons of people are entering the field thinking they can do it, either straight out of college or second career, and they simply can't handle the demands of the classroom. I'm going on year 7 and I'm there to stay. But the demands, especially at the high school level are insane. K-6 is easy because they are lacking one big component. Athletics. That changes the game completely.