This. "developers are quick to pick up the workflow and can create working code and tests during classes/exercises/katas – and then failing in the real world."

This. "developers are quick to pick up the workflow and can create working code and tests during classes/exercises/katas – and then failing in the real world." The anathema of TDD is that people equate having well defined test cases to a solid product that brings the solution that the user wants. I have seen far more software projects boasting of >85% of code coversge for tests, but still failing spectacularly. TDD failed because it was assumed as the magic wand that aligns the end product with what's on spec and the process that it would cover, but the reality of human behavior being merely coded to test cases is far out from reality.