People have roots, yes, and it's tough for people to "just move." But, time marches on and the buggy whip industries ain't gonna make it. That said, yes, economically we can't expect people to move - those mining towns have worthless houses, etc. So, we spend money helping people. I have no issues with my taxes supporting people in making those transitions. It helps the country in the long run, benefiting us all.
No industry is going to be harm free. We're going to mine things, make things, and on and on. But, we can minimize impact. Coal is not the minimizing alternative, not even close.