If something doesn't work, they can communicate back to the (well-bearded) developer who sent them that weird build. The developer surely has some crazy esoteric distro on their bring-your-own device, but they also have desktops running the consistent distro available to them all around the office to reproduce the issue on. It's a bridge between worlds.
I work in academia and we manage our own Ubuntu spin for this reason, despite everyone we ship it to being very conventionally smart.
> if you're smart enough to work at Google, you're smart enough to manage your own OS.
I also like to think of myself as "smart" for self-managing most OS and cloud things. But the role of smarts is probably minor compared to the decade+ of experience I have doing it. When it's something I'm good at, I think it's because of intelligence. When it's something I can't do, I assume the people who can have lots of practice.