Price is just crazy for single tower and there's one variable for Ryzen:It's not that, just the U12A seems to punch well above it's weight for it's size, cramming in 7 heatpipes, despite fin surface area. Considering options is all.
Intel optimized convex base.
Just like in NH-U12A class Mugen 5 and other Scythes, NH-U12A's base has some convexity.
That fits well for Intel's centered heat output and often toward concavish heatspreader.
But AMD has flattish or even tiny smidge convex from center heatspreader.
And two such surfaces results good contact only in small area.
Also Zen2 and probably coming Ryzens have off center heat output with chiplets away from center of package.
That can results far less than optimal cooling performance.
"Lapping"/grinding base flat helps to that, but that's some hours of work along with needing sand paper and piece of glass or something certainly flat.
(on top of already super expensive cooler)
Here's some testing of heatspreader shapes, including 3900X:
https://www.igorslab.de/en/intel-vs...er-really-what-is-better-ryzen-9-or-core-9/2/
And here's before and after lapping testing.
https://www.igorslab.de/en/kuehlerb...amd-and-conkav-reader-test-and-picture-story/