That depends on the guest worker program, of course. I'm clearly older than you, so I remember the one we used to have. The way that worked was that companies who specialized in supplying labor brought seasonal workers to the US. Only the workers came, not their families, so "anchor babies" were rare.
The workers were legal, and had id that showed they were guest workers, but that didn't matter a lot, because the companies that hired them provided housing, transportation, etc. They also provided medical care.
We were assured that the workers would go back home after their jobs were over, because most of the companies withheld about half of their wages until they went back home.
We got rid of that program because Liberals thought it was heartless that we made the workers live here without their families for months; they lived in cabins Liberals thought were substandard; and if they needed any medical care that wasn't just routine, we sent them home.
BTW, we still have a guest worker program of sorts. We have European youth working at Atlantic Coast resorts for the summer. They come here, do the work, and go back home.