Was it?
Why were they printed in the US? That's far more expensive than printing elsewhere, with the savings in shipping nowhere near enough to offset more expensive printing in the states.
Plus, the price remained at $50 despite inflation. Roughly speaking, they are selling the book at a 24% discount when you account for inflation. The margins are already squeezed. Printing in the US is just squeezing them even further.
I wonder if the print run was very short, to get books to market on time. Does anyone have a second printing copy? Where was it printed?