It is tough. On the one hand, I agree with you. On the other , writing tests seems both incredibly inefficient as well as missing the intended purpose. You cannot have a test suite which ‘proves’ the implementation is correct. A test suite is really like Swiss cheese - there are so many holes that implementation code can get through.

Now, bear in mind that I say this as a passionate tester and verification enthusiast. I don’t have a better alternative, so I keep writing tests. And yes, they do catch bugs. I’m not saying they have no value. I’m saying, they always let some bugs through, I.e, they are not complete.

And that makes the cost of them very depressing. Not only cost to write, cost to continuously run.