>almost always takes place far from population centers
No in PRC case, they literally build population centers to service mining, part of third front strategy in 60s to move mining into rugged interior to protect against US/USSR. If you want to mine/process at PRC scale, you need to plop a few million people in large urban complexes i.e. boutou has 3 million people, they're not 5000 people mining towns.
It's amazing how many people think China bootstrapped its industry from first principals when all it did was lure western companies to move their production over and "learned" by copying.
There's a reason western M/HREE (i.e. the strategic good stuff) strategy hedges on similar iconic clays finds like PRC, because that's the only working industrial chain that extracts M/HREEs at scale. It's why AU/Lynas focus on ionic clays and not US hardrock... which btw doesn't even pretend it will do anything meaningful for mineral security other than light REE.
US+co is trying to replicate PRC M/HREE industry, without the techstack that took PRC decades to build out, because US+co never developed these geologies in the first place. The relevant upstream extraction/mmidstream refining tech for kind of deposits was never pursued in the west.
Now west can move fast due to second mover advantage, but it's going to be slow going like PRC EUV. Until then it's going to require all sorts of parallel efforts like recycling, or materials engineering to reduce M/HREEs to mitigate gap.