I did watch a video about the processing of some of the rare earths, to refine three of them a series of ion exchanges were used, very interesting but I can see why they’d be so expensive.
Government subsidized energy
Criminally cheap and unsafe labor
No cares for the local environmental effects
It's a cost issue, because in the US or EU none of those three factors are present. Instead we've all 'outsourced' that mess to China.