There are a lot of people who can't run a mine or start a new one. There are very few who would chose to work in one. How is it determined who 'must work in one' (coal mine), and who is free to pursue another job like park ranger? I'm also curious what 'must work' entails.
Doctors may like being doctors, but I'm sure there are more who would sign up to be neurologists than gastroenterologists.
Coal mines still employ a great deal of human laborers, even the few that are highly mechanized. And it's still difficult, dangerous and not very pleasant work. Most coal mining is still done underground and even surface mining is quite dangerous. See e.g. <http://en.wikipedia.org/wiki/Coal_mining>;
It's also usually not a good idea to act condescending when you think you have superior knowledge, as then you may look foolish when it turns out you are misinformed yourself.
Automation of mining is inevitable. Everything is actually.
It's like saying people still make bully whips just as cars are starting to hit mainstream - you are correct about the present - you are wrong about the future.
Oh, and the doctors take less pay because they like being doctors.