Students are free labor. They aren't racking up six figures of debt not to be exploited.
"Student volunteer" probably refers to undergrad students who are working on their theses.
Ah, then it's okay not to pay the going rate for the labor.
A lot of students benefit from this unpaid labor. I know many people who volunteered in labs to get real experience that they translated into high paying jobs else where.
Those people would not be able to get the job if it was paid
They used $4.5m worth of equipment. They didn't purchase it just for this test.