Jobs cared deeply about the details, both UI and UX, it's just that the details he cared about and how he prioritized them might be ones you and me disagree with. He almost never sacrificed form for function, but he certainly did care for both.

That attention to detail was one of the reasons people loved Apple products and why so many Mac-only or truly Mac-native apps exist. Contrast with windows where most "native" apps are either Qt-based or some WPF monstrosity full of custom controls. Microsoft Office has its own UI stack ffs.

That doesn't mean his vision was always good though, or that he was a good designer (he was good at picking things and making sure they fit, but he didn't come up with them himself)... Some decisions are just baffling to me, seriously how long did macs stick with 1 button mice?

“It just works” used to be a motto. One of Jobs’ most quoted phrases is “design is not just what it looks and feels like; design is how it works”. Snow Leopard was advertised with “zero new features” because the focus was on improving what existed.

There are plenty of other examples, in interviews and stories from internal events, which corroborate he cared deeply about Apple products working well.

Jobs as a QA engineer would be doing smoke tests by "eating his own dog food". He would make sure that at least the fundamental tasks of software/hardware work flawlessly.