Android uses memory controllers that are designed for general compatibility (diverse GPU/CPU types) as opposed to being hardware specific, and this general system of compatibility uses more memory.
For a device (like a Samsung Galaxy) to support the PlayStore, the software that they use has to pass Compatibility Test Suite (CTS) (from Android.) If Samsung modified the core kernel or memory management too deeply to be "hardware-specific," they might break compatibility with millions of apps in the Play Store.
If Samsung or Google abandoned generalcompatibility and built a phone where the OS was hard-coded to the silicon chip, they would likely match or beat Apple’s efficiency.
The trade-off is that they would lose the "Open" nature of Android. Developers would have to write different versions of their apps for every single phone model, which is the exact "fragmentation" nightmare that Google spends billions of dollars trying to avoid.
Android chooses quantity (supporting thousands of devices), while other companies (like Apple) choose quality (optimizing for five). Samsung tries to bridge the gap by throwing more RAM at the problem, which is why your Galaxy might have 16 GB of RAM while an iPad Pro only needs 8 GB to do the same task.
