Question: In the near future the demand for resources only rises due to both a ever growing population, energy and resource crises, and rampant consumerism. Peak oil has been reached, scarce resources like platinum, silver, and other rare metals have been depleted on the surface, and the world is beginning to feel the more drastic effects of climate change such as mass extinctions of animals and strains of crops. In this rather bleak period the major mining companies looked to the seas to solve the mineral requirements of earth. While mining the seas isn't a easy affair the ocean's mineral wealth is virtually untapped.

However instead of using drones to mine both ores and the methane ice the big companies used mainly human labor (with drone assistance), but why? What benefit would human laborers in deep sea rigs have over a aquatic drone?

Note:

The population is fed mainly by cultured meat and indoor+vertical farming hence why the population is expanding even though the climate looks bleak.

Asteroid mining isn't considered a good alternative for earth due to the transportation of the goods back to earth. However if necessary the industry does exist (mainly for the initial space colonies)

The mines would be accessed by either mining ships or for the larger mines maglev trains connected to large underwater bases (with the tunnels dug under the ocean's surface)

Answer: 
The mining companies are being subsidized
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Drones would have been better value for money, but the government subsidizes human labor.
This is done to keep the population (especially the men) occupied and also safely locked away, not giving them a chance to sit around talking rebellion.

This is also the reason space mining is not favored: there are too many places to run and hide once the tech for space colonization exists.
That depends on how much communications the drones require. Radio basically doesn't work underwater, so you can't use it teleoperate something at the bottom of the ocean.

Now, for everyone reaching for the comment button to mention ELF, let's just get it on the table:

<https://en.wikipedia.org/wiki/Communication_with_submarines#Extremely_low_frequency>

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> Electromagnetic waves in the ELF and SLF frequency ranges (3–300 Hz) can penetrate seawater to depths of hundreds of meters...
> 
> 
> 

1. "Hundreds of meters" doesn't make it to the bottom.
2. That 3-300Hz bit means that the entire, world-encompassing band, has about 300Hz of bandwidth. WiFi has a bandwidth of about 22MHz, or about 73,333 times larger. And you've only got to share it within folks of a couple hundred meters of you.

So plopping some folks on the bottom of the ocean gives you some local human intelligence, without having to maintain a umbilical cord from the bottom of the ocean to the top. If the mining installations lasted for extended periods of time, it might be worth running fiber to them from the coastline, but if they had to roam, that'd be less helpful.

Over shorter distances, you'd have a chance of making things like messenger drones, cables, acoustics, or maybe even light transmit data to the drones.