There's a powerlessness to using Android.
It's difficult to just do things. Even windows feels more "free." Phone OSes are built like prisons.
Ideally Android would let you drop into a real shell, without having to deal with android sandboxing.
Regardless, I use termux and tasker to get my automations done.
What are the main things you can do in a real shell versus termux for instance?
It's a pretty big sandbox in my experience.
You can root it if you really want (and if the bootloader is unlocked)
Probably because carriers don't want a bunch of poorly secured devices on their networks.