European distances and built in loyalties keep down costs and keep up revenues that allow teams to survive drops more easily. Pro/Rel as a system in Europe can not be brought over to North America....yet.

The US and Canada are slowly developing the infrastructure of local teams that will eventually allow for Pro Rel to exist - but we are talking 60 years from now for this to become sustainable and given that 60 years ago the biggest sports in the US were boxing and horse racing, I wouldn't want to make that bet.