If you were to log in, you'd be able to get more information on your fellow community member.
People wonder why so few US citizens want to be engineering Ph.D. students. It is the same reason they don't want to be migrant farm workers. Low pay, long hours, better opportunities elsewhere. On the other hand, if the only way I could legally work in the US was for minimum wage programming computers or running tedious experiments, well then it would be an easy choice. Good thing our immigration laws make it impossible for bright young foreigners to do anything else. When jobs like clothing sweatshops and strawberry picking are taken only by recent immigrants, we immediately blame the working conditions. When it's grad school, we blame the students.