[danaris]

The thing is, as I understand it (and someone please correct me if I'm wrong—with citations if possible!), there is no law that mandates that non-full-time employees get no benefits. Indeed, I know of some part-time employees (though still fixed-time, like half- or three-quarter-time, not variable hours like retail or food service generally is) who get prorated or full benefits.

If they are saying their hands are tied, it is because there is an institutional policy of not providing benefits to those who are less than full time, not because they are not allowed to do so.

In other words, if they implied that they can't do this because of US law, they were lying to you.