Like you I've been puzzled by the difference in the US and EU pricing for MFDB's. It appears that the market in the US is more open with less controls. Maybe I'm wrong on this. However, I wonder if this restrictive pricing behaviour is even still legal in the EU anymore? I don't think I'm allowed to purchase a MFDB from whatever country I choose!
What puzzles me most is that in Japan, a P45+ costs 5.200.000 Yen list price, which is about 42.000 US$... that nearly twice as much as the price you mention above. From what I have heard, it seems difficult to negociate much below list price around here.
The Japanese price makes sense relative to the EU price in Euro, but if Phase is not loosing money selling it at 22.000 US$ in the US, then they/their dealers are making totally outrageous margins in EU and Japan.
Another thing that amazes me even more is the price of the Leaf backs in Japan. A A75s goes for 4.400.000 list price, although there is zero reason why Leaf would be affected by the very strong Euro/Yen change rate. They have simply aligned their Japanese prices with Phase (considering the slightly lower market value of their 33MP offering compared to Phase 39 MP), although they get their sensors from Canada and much of the rest locally in Israel. It would appear that they make even more money on photographers in Japan...
Very concretely, I could consider investing into a P45+ at 22.000 US$, but there is no way I would think of paying 42.000 US$... Considering a 3 years plan, that makes a 7.000 US$ difference a year, not even considering the cost of credit.
Mamiya is going to hit those guys hard everywhere, but even more so in Japan. The Mamiya back goes for 1.000.000 Yen here, which is 3 to 4 times cheaper than the corresponding Leaf/Phase 22 MP offerings.