They may have no idea how they are built, but they do notice how janky and out of place they are. Take for example Microsoft Teams, have you ever met anyone who actually likes that app? It's insane that a simple chat app uses well over a gigabyte of RAM.
It's absurd that one of the biggest software companies in the world can't seem to produce a sleek, native app. It's purely a cost saving measure. They decided mediocrity is good enough for them and they get away with it because the people making the purchase decisions are not the people who have to use it daily.
For their own operating system that they own the APIs and development tools for, no less!