Even though most people claim to be enlightened, most don't like Cadinot films because of the interracial sex, especially because the blacks are often aggro tops.
Movies from Spain are nothing special either because many of the actors look like the Mexicans in your neighborhood.
Outside of Cadinot, there were no decent porn makers in Europe. Much of it was very amateurish.
Another issue is that some countries allowed porn with 16 yo actors {this stopped about 10 years ago}, so they were banned in the west.
Economy is a factor, as I mentioned about the high costs in the UK.
I think you are over generalizing things. Eastern European porn actors come in the same wide range as Western porn actors. At one point, American films went away from twinks and someone had to fill the gap in the market. Now everyone has twink movies to spare.
