[rmk]

Well, one of the problems is the pronounced tilt toward family migration, which occurs at the expense of highly skilled migrants. There are no political points to be won by encouraging legal, high-skilled immigrants, so they are treated like dirt while illegal immigrants' concerns (e.g., dreamers) rise to the top of the pile.

Another problem is jus solis, which enables illegal immigrants to lay claim to public funds indirectly via US-citizen children. The large number of illegal immigrants makes this a problem. If their numbers were better controlled by prompt enforcement of existing immigration law, then most people would simply not object to providing a high level of assistance to a small(er) number of illegal immigrants. However, the large number of illegal immigrants coupled with a low-medium level of assistance creates an underclass that will remain on the lower rungs for generations.

The last problem is the "refugee" problem. Because family and skilled migration are the only other legal paths available, many people abuse the refugee provisions by posing as victims of political violence, domestic violence etc., in order to gain entry. This has blown up into a huge crisis at the US-Mexico border.

A significant number of hispanic immigrants and citizens are in one of these problematic categories, and the sheer scale of the problem is the actual issue.