The drivers part is easier to answer. Where Linux started drivers were compiled into the kernel. A few years later modules came along to dynamically load drivers (and other things). But modules could still (and can still) crash the kernel and the drivers don't necessarily have a particularly stable interface.

Compare this to Windows. Drivers were once the bane of Windows and a huge problem for stability. Microsoft invested heavily in this and it seems to have worked. The Windows driver interface is I believe stable and has been for many years at this point and drivers themselves are more insulated from the kernel. Not completely but it's better in many aays.

Android really has its hands tied here by what Linux does. You may agree or disagree with that but the above is a view held by influential people within Fuchsia.

The ecosystem is really around the process by which updates are released. This is a tedious process of maintaining many Android trees and updating them with new Android releases. These need to be patched onto the existing trees or the changes made to the existing trees need to be ported onto the new Android tree. This is a nontrivial task either way. It's why Android phones get limited updates and those updates can lag behind the official release by months or even years.

This isn't a situation Google likes so some want to make the manufacturer responsible for less, most notably the drivers.

Remember that Samsung is motivated to sell handsets, not update existing handsets.