> If you some up all immigration to Europe, you suddenly see that the US isn't quite the leader you think it is.

Geography puts a lot of constraints in who can travel where.

A lot of people came in western Europe from Afghanistan or central Africa by walking [0]. You need two months, so it's not an insurmountable task. Most dangers come from predatory people.

Walking to US could be done from central or south America. A similar feat would be going from Bogota to San Diego. Yet it means much less people are in situation to walk to US than to Western Europe.

[0] https://www.google.com/maps/dir/Kabul,+Afghanistan/Calais+Eu...