> Past a certain level of executions

I don't think complexity is the right metric. The listed companies still do write a lot of shit software, but mostly smaller things you don't see much. Anything in the 'fast path' of these companies is getting executed trillions or quadrillions of times and because of that any bugs will become shallow.

I think you can scrap Microsoft there when it comes to their pc stuff and their mainly B2B stuff (dynamics and the like) As for the rest other than apple I think pageloads are an obvious metric to track and there's always going to be a contingent of their programmers incentivized to care about their code quality because slow code and the like runs on their machines at such scale that it often costs them a lot of money, same with uptimes of various services. Their amount spent on wages is comparatively very low.