Android is a Linux distribution unlike any other. They use a completely different framework for drivers for hardware, they have their own patches for binder and other things that see no use outside of Android and will never get upstreamed. They have their own libc which is not used in any other distro. Very little of the work that has been done to make Linux work better on Androids has benefited the rest of the Linux ecosystem. Even the WiFi/Bluetooth drivers, which is a massive shame.
Binder has been part of the mainline kernel for quite a while.
Also drivers for things on Android are for the most part done by third party manufactures and so its up to those third parties to upstream them. No different than any other driver used on more generic PC or server HW.
Also you realize that there's like 3 or 4 different libc projects for Linux distros to use right? Bionic isn't special in that regard.
>They use a completely different framework for drivers for hardware
No, both use kernel modules or statically compiled code for the part of the driver that actually talk to the hardware.
>they have their own patches for binder
Binder is part of mainline Linux, but yes I guess technically there are some patches that are related to binder, but remember that Android works on a mainline kernel.
