"suppliers must limit the number of student workers they use and student work must also complement the students' primary area of study, HP said."
Imagine if U.S. employers or their customers enforced such a policy here. It is preferable, of course, for students to get private employer internships or on-campus jobs that are related to their field of study. Many students don't get those, however, and simply need to work to make money and pay bills -- whether the job is fast food, waiting tables or whatever.
I'd like to ask my fellow engineers here, what kind of non-engineering-related jobs did you have when you were a student? I'll go first: cashier at a gas station/convenience store during freshman & sophomore years. Later I got a job with the EE department as a teaching assistant, but I'm grateful that there was no policy to protect me from being "exploited" by working at a job unrelated to my field of study, or limiting the number of students that employer was allowed to hire!