Even bad teachers have to meet the standards, which are usually set by law. A preschool teacher, who often gets paid just over minimum wage, usually requires a 2 year degree (for head start-like programs). A teacher? 4 year degree, with a preference for a masters and in many places, absolutely no pay during the summer months.
It isn't like any other industry hires only "good" people, though, so calling out teaching for that - especially if your area has a shortage - seems a bit unfair.
But those standards doesn't mean anything if they are still bad teachers. Would you hire a software engineer with a 4 year degree who can't code? No, of course not. But would you hire a teacher with a 4 year degree who can't teach? Of course you would! You just need them to tick a box, their skill as a teacher isn't relevant, if they have a piece of paper they meet the bar and are hired.
I suspect that perhaps you are not a teacher, and have never applied for teaching work. Or maybe you live somewhere where school hiring practices are very irresponsible.
My daughter is a teacher who has just changed jobs. The process was something like this:
* Apply (CV, plus extensive covering letter)
* Prospective new head knows old head (they all know one another) so they talk
* Candidate gets an interview, and has to prepare a class
* Interview day: candidate delivers prepared class, observed by head and head-of-year
* Candidate is interviewed at length by a panel of three teachers, including head
* Decision made subject to references
* References taken up; award position
What you've described is a process that isn't even appropriate for a supermarket checkout clerk.
In general, teachers start out with a bit of experience as most schools require teachers to, you know, teach as part of their schooling. In other words, you simply aren't hiring someone that doesn't know how to teach and has demonstrated it in the classroom.
Companies also fire a lot of bad software engineer and have technical interviews so there is pressure to perform. You never see teachers fired for being bad at teaching. They only get fired when they do something illegal like harass their students or when they refuse to go to work. If companies hired every person with a CS degree from any school to work as a software engineer and never fired anyone for bad performance you'd see software engineering salaries sink like a rock as well.
> They only get fired when they do something illegal
Here in the UK, people have employment rights, including the right not to be dismissed without process. That involves warning the employee twice verbally, putting in place measures to help them improve their performance, and then a final written warning. Teachers here are unionised; they can take their employer to an employment tribunal, which is a kind of court, for the offence of Unfair Dismissal. It takes time and money to fire someone for underperformance.
Consequently recruitment is done rather carefully - more carefully than in many software companies, judging by the calibre of some of the colleagues I've worked with.
FTR I used to be a school governor in a state-run primary school.
It isn't like any other industry hires only "good" people, though, so calling out teaching for that - especially if your area has a shortage - seems a bit unfair.