Most teachers want to do better, but are stuck in a system where they're not able to. Overwhelmed with large classes, small budgets, ridgid programs, demanding parents, it's hard to also dedicate energy to reflection or student attention.
The fact that, outside of the expected exceptions, a skill/subject/section is never brought up after the test means that teachers are not thinking at all about retrieval practice. There is a time for understanding and justifications, and a time for saying things as they are.
Then, my personal experience and that of my friends, who all attended mid- to high-ranking schools outside the United States, is that regardless of class size and teacher workload, teachers never seemed to know how to teach effectively and efficiently.