“without pay” is a real problem - and, note, those aren’t terribly cheap clothes those young people are wearing. There’s a lot of problems with internships, problems that straddle race and class. But: there’s an awful lot of nonwhite young people who already live in DC, whose parents are covering their room, their board, potentially their health insurance; “no pay” would be a hardship, but less crippling than for someone from out of town. It’s not like it would be difficult for a Congressperson or their chief of staff to visit local schools and encourage people to apply.
… or are interns from a congressperson’s home district? Because that would be plausible, but it would make the “no pay” thing really extra abusive.