I guess that confusion comes from you don't know how OS works. So you compare RAM usage between 2 different OS and think it comes from "memory optimization deficiency" by one.
As matter of fact, OS do not optimize the RAM usage of an app. OS just try to allocate as much as app request, no more no less.
That is not entirely true. Also the OS consumes memory too. If you can create an OS will a more stable and smaller memory footprint you can improve device performance. Its a very intricate balancing act. Using resources and saving resources for applications.
I don't know how OS works? I am embedded device engineer... Not going to get in a pissing match about this though.