But I'm curious, do you think the rules are only applied to some countries in the EU and not others?
It certainly looks that way. Show me that the EU are punishing Germany with fines 84x what they're fining Poland and I'll reconsider.

I'm guessing that the problem with the mine is that it's on the Czech border and therefore it's pollution is spilling over into Cz. What do you think?
This is a factor. But guess what? Germany have coal mines on the border with Poland.