[mikepurvis]

The people being conquered in Europe were also a lot less vulnerable in several key ways— my understanding is that they were largely overwhelmed by superior military tactics and infrastructure (roads and so on), but once conquered they were at a similar level in overall technology and well positioned to participate in the larger Roman economy.

North American native peoples faced new infectious diseases that they weren't at all prepared for, a huge technological disparity (guns), and a lot of predatory economics (trading away valuable furs for beads and trinkets).