Much of what you’re describing (besides the live hitching and unhitching) is made possible by Communication-Based Train Control (CBTC) [see link below]. This has been implemented in many rail systems globally, mostly urban rail. It helps reduce headways a lot. However:

1. It’s not just a software problem - installing the hardware is time-consuming and expensive. The engineering requirements are much stricter when human lives are at stake so you can’t just strap on a radio to each train. You still need additional infrastructure along the tracks to manage communications.

2. There are other limiting factors in reducing headway - having enough trains and having enough train operators. Somewhat easier to solve perhaps but still costly and non-trivial.

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https://en.wikipedia.org/wiki/Communications-based_train_con...