No one suggested that, just you.
Corrupt greedy contractors hire illegals to do the actual stoop labor to maximize their profits. This is no secret and in fact illegals completely took over the construction industry years ago. Even those drooling in cups know this. Those bankrolling these project winked and nodded as it maximize their profits..
Profits regardless of consequences...
Not saying there aren’t any illegas in the construction business, but the folks who are responsible for inspecting the rebar before the concrete is formed are who to blame for this.
I worked as a contractor for many years. Some of the best rough carpenters I have ever seen were (probably) illegals.
As a whole, Mexican construction workers are better than white American ones, though not necessarily cheaper.