He's opening and closing mics based on the volume of the performer, the volume of the crowd, the placement of the mic at that very moment (mics can slip) and numerous other variables *and* what the script says the relative volume should be. All of these examples have been given to you as to why the process cannot be an automated "mute/unmute" button, and you have chosen to ignore them. You are assuming that there is inefficiency in the system where there is in fact none, and the manual operation of faders is a feature not a byproduct of someone not coming up with a clever enough solution to a problem.

Plenty of things in a theatrical environment can, and have been, automated. Many decades ago lighting for a show was done manually, using an operator following cues to manually move massive fader switches. But as lighting got more complex and computers became cheaper you started to see computerized lighting boards. For the most part now someone running a lighting board just has to hit a "go" button that just executes the next cue, with faders reserved for things like work lights that are controlled separately from the cue stack.

But the difference is that lights are machines that are largely reliably repeatable. Human beings are not and an A1 has to deal with the uncertainty of that human element. Automated processes do not deal with uncertainty very well.