IIRC the way it’s implemented is by rendering 2x and downscaling, so sometime’s it’s not as pixel perfect as Windows. But the simpler implementation for software developers meant they had like a 10 year head start compared to Windows where software takes a long time to support up new OS features.
There were intractable issues with window spanning across displays with different scale factors. Ultimately this was resolved by not allowing window spanning on the platform anymore.
You can still window span on macOS. You just have to disable the feature that gives every display its own workspaces.
Not that you’d ever want to do that. At least I can’t think of a single good reason why anyone would want this.
I find this a strange complaint, (not saying you’re wrong!) as to me more pixels should mean better rendering of elements, not dictate their size.
To be honest, the DPI on this monitor is a little too low... I have a QHD 27" on another machine, and that seems 'just right' (for my eyes).
If 4K monitors were the same price as QHD ones for the same screen size, then maybe I'd re-consider, but whilst they are sold at a premium, I'm not interested.