Some amount of human labor will be required for operations, say maintenance of the in-situ automated systems, or intervention when things go wrong. These costs can't be eliminated with renewable energy, and won't be fixed with robots for some time yet (decades, minimum).

And if a mine can be automated to yield orders of magnitude more material than recycling for the same labor costs, you would need some other financial incentive (government subsidies, backroll by Tesla for marketing purposes) to make it viable.