There's also the fact that you're selecting for some of the worst teachers by confining them to curriculum and harshly punishing deviation or expansion. The best teachers are good precisely because they do those things, and if you take that away it's not the same job anymore—they're just reading a script and serving as a mouthpiece for the state rather than serving the students the best they can. That's not what they signed up for. They'll leave.

Check teacher forums, this kind of over-management and micro-management are major reasons for discontent in the job, and one of several factors pushing good teachers out of teaching.