So why the 'spanish 'builder, I wonder? Alien contractors just doing the work that domestic contractors won't do?
Because they had the highest bid. Cintra-Zachry (Zachry being an American partner based in San Antonio) is the lead company, but they will surely subcontract various components during construction, just like any other company would do with any other road project. This company is no more likely to use illegals than any other road construction firms, in case you missed it Mexico won its independence from Spain long before you were born.