The is an enormous amount of environmental activism that exists to achieve an ideological result, it has nothing to do with science or a reasonable analysis of tradeoffs. They cynically exploit people’s ignorance of the subject to justify their actions.
A well-known example of this were regulations that require super-low arsenic levels in water. The thresholds were set extremely low, far below natural levels in most mining districts. The proposed limits were so low that ironically it would put some populations at risk of arsenic deficiency — arsenic is an essential micronutrient in animal biology, much of which comes from water. The people pushing to set levels so absurdly low were anti-mining activists.
If you operate a mine, that benchmark for water quality is now your problem, even if the natural levels are much higher. This puts the mining operation in the somewhat intractable position of remediating the arsenic levels of ambient nature as a pre-condition of mining. You can’t just ensure the arsenic is at the level it was when you found it, you have to reduce to some idealized standard that can be intractably expensive to meet and has no scientific basis. It is exploitive and ugly by people that don’t care about the long-term implications as long as it serves their short-term ideological purpose. Civilization requires mining, it does little to help the environment by exporting it to other countries.
I’m a major nature lover and conservationist, grew up in remote rural areas, and spend more time in the deep wilderness than most, but I am also a relevant scientist by training. The amount of scientific malpractice that happens under the pretext of “saving the environment” in the US is pretty damn gross. There are good people inside the Department of the Interior that try to mitigate the worst excesses but the onslaught is unrelenting.
On the specific point of rare earth mining, the chemistry of rare earth ores are naturally unpleasant, much like gold and silver ores. For historical reasons, the massive deposits of gold and silver in the US were developed before any real regulations. Some of those made quite a mess (see: silver mines of Idaho). Modern versions run quite clean but the hurdles to opening new mines are so prohibitively expensive that the US mostly only still operates the grandfathered pre-regulation mines.
REE mining has none of these advantages. The demand for REE is almost entirely modern, so none of it was grandfathered in. I’m sure the US could operate them at a level that is adequately clean but there is a huge contingent of activists that are against all mining and refining on principle and use the myriad levers created by policy over the last several decades to make sure that never happens in the US.
That said, a few months ago the US government announced a strategic investment in the largest REE deposit in the world, which happens to be in the US but has spent most of its time in bankruptcy. I have to imagine that the intention is to streamline production under some kind of exemption.