Testing also includes manual testing. Programmers that do not write tests, spend a lot of time making manual, disposable tests.

About speed, there are several studies that conclude that TDD is faster. The main reason is that manual testing, and debugging, takes more time than most of the programmers think, but there are also additional do-overs because of bugs.

Anyway, I did not put scale because I preferred to avoid this discussion. The main reason is that several programmers have problems with TDD because they follow Waterfall standards rather than Agile standards.

The difference between Agile+Refactor and TDD is having reliable tests. If you write tests, but after code, you cannot trust on those tests. Without tests, or without trustworthy tests, programmers fear change, and refactors are done less frequently. Instead, TDD forces consider refactoring every 30 seconds or so, and tests are highly trustworthy.