One use of rare earths is for permanent magnet motors. Induction motors don't use permanent magnets, but they tend to be significantly less efficient. Permane

One use of rare earths is for permanent magnet motors. Induction motors don't use permanent magnets, but they tend to be significantly less efficient. Permanent magnets can also be made without rare earths, but I expect the result would be a physically larger/heavier and/or less powerful motor. So, it's a trade-off.