But they have to be mapped into RAM, right? And if the OS can't unify those distinct images because they're in different paks, isn't my RAM now being eaten up by clone static data that I could instead be using for actual work?
https://blogs.gnome.org/alexl/2017/10/02/on-application-size...
I can't speak for the others, but Flatpak is a layered solution, so files are deduped and shared across the layers (runtimes, applications) that need them.