They don't have a Steve Jobs anymore to sit down with the product, get frustrated beyond belief with it, and start sticking boots up asses on general principle.
Nobody is going to step up to do that because all the other executives would hate them for it and knife them in the back, and it would be seen as a waste of effort. And nobody could ever tie fixing those bugs to making a financial number go up, and would argue instead that it was pure cost for no benefit.
I know at work I get work around windows taskbar jank at least a few dozens times a day. Granted, I can't do anything about it.
Instead, seemingly trivial bugs exist in huge software products for years. It somehow feels like the people in charge actively avoid dog fooding their own products.
Fixing broken UX is not a priority at Apple any more. They stopped enforcing HIGs for 3rd party apps a long time ago, and their own apps violate many principles that used to matter. Music app on iOS is a great example of slop UI.