You say "At the end of the day, tests exercise and lock down behaviour of code." That's exactly why tests can be expensive! If your UI is changing rapidly the t

You say "At the end of the day, tests exercise and lock down behaviour of code." That's exactly why tests can be expensive! If your UI is changing rapidly the tests try to lock things down when they shouldn't be locked down. Sometimes you want stability. Testing for stability is worth doing then. Sometimes you can't have stability, and automated tests are just an expense. It all depends on situation and goals.