1. I didn't say illegal immigration was a major cause of low wages, but it definitely does have an effect, especially among lower class workers. You say "Undocumented people mostly do jobs Americans refuse to do," but the issue is that Americans refuse to do it for minimum wage. Why would someone do backbreaking labor for near minimum wage and no benefits when they can work at a gas station making more? For Americans to do those jobs, wages would have to go up. Corporations would be forced to do so if illegal immigration didn't keep wages down.

2. That site that you linked to is ridiculous. They measure racism by peoples' beliefs in self-determination and whether or not illegal immigrants take jobs. Which they do. If there are 10 million illegal immigrants in a country of 300 million doing lower class work, and those people aren't equally distributed across the country, you can bet there will be pockets of land where lower class wages are suppressed. And you can bet that, within those areas impacted, views towards illegal immigrants will be more negative.