more people might die at yellowstone (idk), but they have such a huge number of visitors the actual percentage of deaths is tiny. North cascades is one of the least visited parks.

In absolute numbers more people die at Yellowstone. North Cascades has a higher number of deaths per 1000 visitors, however.

This is in large part because North Cascades is a lovely park best known among serious alpine climbers. So many of the people that come to North Cascades are there to do something risky. Most people that come to Yellowstone are there for light hiking, camping and tours, low risk activities.