Re: Not talking about "Mexicans" here
If they were Mexican engineers then they'd have a hard time getting an H1-B visa. They're effectively monopolized by a handful of Indian IT companies that specialize in outsourcing or, more accurately, replacing American workers by lower cost Indian workers. (....and there's a lawsuit about this:-
https://www.mercurynews.com/2018/08/16/h-1b-indian-outsourcing-firm-discriminates-against-non-indian-workers-games-u-s-visa-system-lawsuit/ )
The H1-B visa is a mess; instead of it giving people who are needed opportunities to work in the US the system has mostly got rigged and, to add insult to injury, renewal is now a lottery so there's absolutely no job security. (I personally know one person who had to let a worker go because she lost the renewal lottery -- and it wasn't an Indian IT worker, it was an Italian accountant.)