I think a big part of the assumption even among liberals or leftists that H1-Bs are paid less is the belief that non-Americans must be less qualified. I think a lot of people are not ready for the idea that things are actually currently rigged in their favour; that there are tons of people from other countries that are more skilled or educated or otherwise qualified than them and that resources being concentrated in the US actually are giving them a giant advantage over most people in the world