Earlier quoted context omitted.
The "most engineers" not "most engineers we've hired". But also "most engineers" aren't very good. AIs know tricks that the average "I write code for my dayjob" person doesn't know or frankly won't bother to learn.
Even speaking from a pure statistical perspective, it is quite literally impossible for "AI" that outputs world's-most-average-answer to be better than "most engineers". In fact, it's pretty easy to conclude what percentage of engineers it's better than: all it does is it consumes as much data as possible and returns the statistically most probable answer, therefore it's gonna be better than roughly 50% of engineers.…
For most engineers the ability might be there, but the motivation or willingness to write, for example, 20 different test cases checking the 3 line bug you just fixed is fixed FOR SURE usually isn't there. You add maybe 1-2 tests because they're annoying boilerplate crap to write and create the PR. CI passes, you added new tests, someone will approve it. (Yes, your specific company is of course better than this and requires rigorous testing, but the vast majority isn't. Most don't even add the two tests as long as the issue is fixed.)
An AI Agent will happily and without complaining use Red/Green TDD on the issue, create the 20 tests first, make sure they fail (as they should), fix the issue and then again check that all tests pass. And it'll do it in 30 minutes while you do something else.