Nearly half of the workforce of crop farmworkers in the US is made up of "illegal" immigrants. The US food-supply relying on those people has meant that, in practice, immigration law enforcement is deliberately selective and self-serving.
So, the idea of illegal immigration as a vice worth cracking down on and punishing has not been consistently applied by the people publicly condemning it (like this current administration), meaning there is a very real sense in which the distinction between illegal and legal immigration is not real.
"The people"? Are you sure you're not committing the common sin of conflating vocal people with most people? For example, I publicly condemn illegal immigration, regardless of which industry said immigrants are propping up, while at the same time recognizing that such industries need to be carefully extricated from reliance on illegal immigrants and also that the management of immigration and the definition of illegal immigration needs to be fixed.
As another disconnect, farmers overwhelmingly voted for Trump. I really don't understand how people are using their brains any more.