First, I object to the idea Every teacher gets to decide
what they teach. There is a very prescriptive list of what the curriculum must contain, and it is assessed by standardize tests.
Second, teachers aren't fungible robots. They are humans with personalities, interests, and passions. Education works best when teachers are engaged. I think you underestimate the value provided by flexibility. you might be able to reduce variation through standardization, but that doesnt mean you improve the mean. My very best teachers went off script, teaching more valuable information, like a 5th grade teacher that decided to teach business, html, and the scientific method.
Last, it isn't exactly anarchy. Many subjects can be taught from texts, which are organized along standardized approaches.