You could ask the same thing about tests themselves. And I'm not talking about tests that don't exercise the code in a meaningful manner like your assertions on mocks(?!)
I'm saying you could make the same argument about useful tests themselves. What is testing that the tests are correct?
Uncle Bob would say the production code is testing the tests but only in the limited, one-time, acceptance case where the programmer who watches the test fail, implements code, and then watches it pass (in the ideal test-driven development scenario.)
But what we do all boils down to acceptance. A human user or stakeholder continues to accept the code as correct equals a job well done.
Of course, this is itself a flawed check because humans are flawed and miss things and they don't know what they want anyhow. The Agile Manifesto and Extreme Programming was all about organizing to make course corrections as cheap as possible to accommodate fickle humanity.
> Like, what are we even doing here?
What ARE we doing? A slapdash job on the whole. And, AI is just making slapdash more acceptable and accepted because it is so clever and the boards of directors are busy running this next latest craze into the dirt. "Baffle 'em with bullsh*t" works in every sector of life and lets people get away with all manner of sins.
I think what we SHOULD be doing is plying our craft. We should be using AI as a thinking tool, and not treat it like a replacement for ourselves and our thinking.