Because not even the latter is true. They are not rejects of society. I know more illegals immigrants than I know legal ones and I don't know a single one of them who has turned a criminal. In the other hand, their relatives, the ones they came to meet here, are in prison (all legal by birth by the way). Mr Trump needs to stop hating. I am not Mexican. No, nowhere even near. I am hispanic by language but not Mexican. My wife, a Mexican-American, has worked in the fields since age 12, right along with all those illegals that Mr Trump alleges to. No one was ever raped or killed. They work hard and is because of them that we can enjoy a lot of the things we enjoy today at the prices we enjoy. They are hard working family loving individuals and some americans have a lot to learn from them. When was the last time you saw a hispanic asking for a handout at a stop light? May be selling stuff, but certainly not asking for money.
Most of those that are criminal, have most likely come escaping prosecution or as part of their shady business. Happens all the time and they are a minority in comparison.