It's really staggering how much impact one engineer can have when working on a product used by billions of people. Fixing just one of these issues would instantly be the most valuable thing that person ever does in their life by orders of magnitude. We have incredible leverage in the software world.
Trouble is, at that kind of scale even your bugs have users.
You'd be surprised how many Apple engineers are fixing many bugs, of this caliber, on a semi-regular basis.
That "Human Hours Wasted" is not just sitting there because engineers don't care about it, it's because there are many many other opportunities to save similar amounts of time. Crashes waste time, perf bugs waste time -- and security bugs are much worse.