Because the Android one is a stupid paradigm. Linux already contains a layer that is designed for handling bazillions of processes that are doing nothing, and it will transparently swap them out when there is memory pressure. As long as there is swap, which for some reason Android seems not to have.

The fact that some idiots decided to implement a new layer on top of this one that for some weird reason forces developers to manually implement checkpointing (aka saving and restoring state) into each and every small application is something I cannot understand. Possibly it has more to do with Android's PalmOS roots than anything else.

Great, so apart from the already existing separation between the terminal process and the bash process (whose only relation is that one is the controller of the other's tty), I have to make up an extra third process that was previously not needed just to fit into this weird reinvention of the wheel. And invent a new IPC paradigm (in Java nonetheless) to communicate the terminal controller with this new third process.