This brings up the question of a value derived from intern's presence. At my first employer out of college non-technical departments hired (unpaid) interns willy-nilly, figuring half of them would turn out to be bozos competent only to run a copy machine or fetch coffee for the team.

Since engineering department paid their interns, they always had to work out some project plans and business necessity in order to have the position(s) open for the summer. So kinda obvious that many students did not get a chance to intern, as with paid internships the company was way more frugal and selective.