MacOS does seem to “use all the ram” but never falls over itself.

I think the kernel is likely genuinely better in low memory conditions (its hard to be worse than Linux here to be honest) - and thats combined with being aggressive about using as much of the ram as there is available opportunistically. (not fully unloading applications when closing them for example).

“WindowServer” uses 2-3G of ram, and electron apps use lots too; but truthfully my macbook is able to sustain significantly more open programs than my linux laptop, despite my linux laptop actually having more memory. (32G vs 24G for the Mac).

I cant explain it and I am genuinely curious how this is the case, but at least anecdotally, parent is more correct than not.