Only because the extraction process is dirty and we aren't willing to do it as cheaply. Waste from mining other minerals is rich in REMs, and deposits are plentiful. "Rare" is actually a misnomer:

https://foreignpolicy.com/2010/06/15/are-rare-earth-elements...

So it's pretty much like Uranium then. It's not rare, but we outsource its mining to autocratic regimes, because they're willing to produce it cheaply (while destroying their environment).

Pretty much.

Worth shouting out that it is also sourced in former colonies that still have major dependencies on their old imperial masters. Niger/France have this relationship and Niger produces the majority of uranium used by the French nuclear industry.

Photovoltaics do not, in fact, depend on rare-earth elements.

Wind turbine generators often, but far from always, depend on rare-earth magnets. Batteries often (but far from always) depend on other rare, but not rare-earth, elements like cobalt.

Also, the term rare-earth metal is really unfortunate. About half of them have no practical industrial use. The other half is neither rare, nor particularly expensive

The three most important rare earth elements are lanthanum, neodymium and praseodymium. The first two are about as "rare" as copper or nickel. Praseodymium is less abundant, about the rate of lithium or lead. Neodymium costs around $50 per kilo. About 3 kilos is necessary in an electric car. One container full of neodymium ingots is enough for 30,000 electric cars. It's not a geopolitical ace up the sleeve it's made out to be

Ytterbium used to be (carefully) splattered all over the screen of every color TV, to fluoresce red.

Erbium is used in nanogram quantity in optical fibers to amplify signals purely optically. You shine a light on a fiber doped with it and the signal gets stronger.