I'm not sure I agree with you here. Tests are still only as clever as the person writing them. This means it's rarely going to catch corner cases that the developer wasn't already aware of.

I think the real value of tests is exposing expected behavior to teammates, and then providing quick sanity checks against that expected behavior.

The biggest thing new developers miss about testing is that most times you're not writing tests for yourself, you're writing them as a courtesy to your teammates.