I have a feeling a lot of it is to do with the economics. Right now it costs 11k per year per student in America. Then if they are poor, welfare for the parents, healthcare etc..
So by the time the person is ready to enter the workforce we are talking like 300k per person. And thats an upfront investment before it starts paying back. Meanwhile if a 20 year old Mexican comes across the border it costs the government very little. Even if they have to give 500 bucks in antibiotics, its nothing compared to 20 years investment at over 10k a year.
This immigrant then pays taxes even if illegal. For example when they buy something from a store, they are paying the property tax on the store, the regulatory fees, the sales taxes, the tarriffs etc. And wherever they live, they are paying hte property taxes, and in a way they are pyaing the income taxes of every legal person they do business with.
From the government's perspective the more of these freebies the better, thrown into the economy.
After they span the border areas, you hit the anchor baby capitols and hell towns of the southwest. Entitlement areas ... I"M HERE and I "DROPPED ONE" (babies), more than likely several ... you pay me and I'm staying here ... OH, BTW, I'm sending for the abuela!
Or hows about, we make sh*t because capitalist American outfits hire us for slave (see 14th amendment below) wages even though we chose to make our way here illegally of our own accord.
The 14th Amendment needs to go down in flames. It's 100+ years overdue!