Android is like that too. Some devices have non-integer pixel densities (multipliers or device pixel ratios or scaling factors or whatever term you prefer), especially 1.5x aka "hdpi" that was popular around 2011. You can provide separate resources for each pixel density if you still use bitmap graphics for some reason. Oh and there's also "ldpi", which is something like 0.75x, though there were very few devices with it.

With how advanced macOS graphics stack is, I don't understand why does Apple not do this, instead insisting on using integer multipliers. Some iPhone models, too, render the UI at 3x and then downscale it to fit the screen. Even more curious is the fact that they have returned it as a float for as long as retina displays were a thing: https://developer.apple.com/documentation/appkit/nsscreen/13...

edit: one important difference I forgot to mention. On Android, all draw calls on the Canvas, and all view dimensions and other things like text sizes, always take physical pixels. It's your job to multiply and round everything correctly. On macOS and iOS, all graphics APIs take "points", which are those logical pixels you get after the scaling is applied, "density-independent pixels" as Android calls them. I guess Apple thought it would make it easier to adapt existing apps to retina displays. Android has always supported UI scaling, so there was no problem designing the API the way it is.