Interesting.

I'm curious if you're seeing this on desktops? My sample of mac users is very heavily biased towards laptops (and I've only used macos on a laptop) - but I've seen the exact opposite.

Desktops and laptops. I do see more Mac users with maximized and/or full screen windows on particularly small laptops.

(And I'll note that in my own usage, when I'm on my 11" Macbook Air I full screen most apps. But that's a weird edge case due to the screen size.)

Considering how the macOS maximize button works I’d wager this dichotomy is at least partway intentional by Apple, to stop you from falling into the Windows habit of “maximize everything even if it means half your screen is blank”.