Add to this countless hours going into engineering tests that have to bent over backwards and mock the universe itself to test a tiny bit of logic that doesn't make sense to test in the first place. Then multiply with the hours getting lost trying to debug frail tests that break time-expensive continuous integration pipelines.

Good unit and integration tests are a rarity. Instead tests like the above ones which actually are being developed like a side-project to the real project are the norm and they are bogging down the whole project. But you cannot deliver any code that is not "covered" because that would be against the current 100%-TDD bible/best practice/call it however you want.

So the next dev/maintainer has to work out a badly written test (probably bearing untrue assumptions about the programs intended business logic) and after some fun hair pulling he does the reasonable thing which is working around the test or pampering the test to get it to pass. And that is how you end up with test code that is actually buggy and problematic in itself and does not really test much but it is increasing the test-coverage holly counter.