The former government killed 100k jobs in the solar industry when solar power became too cheap for others to compete while whining non-stop about the poor 10k workers in coal mining. They did the same later for wind power and so even now some companies are in trouble as they had to size down so heavily that they can't even get full use out of the boom in wind power now.
Jobs in coal mining are basically an issue for 2-3 local politicians, for everyone else of that former government it's corruption lobbyism and jobs as board members and advisors.
As for why they keep increasing the dig site: It's actually jsut logical. They need coal for another few years and can either increase the area or dig deeper. And the latter is massively more damaging for the environment as it involves a lot of ground water manipulation.