[AnchorAlumna]

No Panhellenic is going to tell you that recs are required. That's not their policy. They might say they're "strongly suggested" or "highly recommended," but not "get 'em or else."
Why?
Because it's not Panhellenic's job to do that. It's the sororities' jobs to get recs. And many chapters still do. It's just that recruitment has gotten so big at many places that it would be impossible for the chapters to solicit recs for every girl coming through. If half of them can get recs themselves, they're that much ahead.
But for the number going through recruitment at Vanderbilt - it's entirely possible that the chapters there managed to get recs on PNMs without the PNMs being aware of it. And yes, sometimes chapters do take girls with no recs - somebody just signs for them.

It's kind of like the girls who swear that only A, B or C sorority are worthy of their membership and lo and behold - they get a bid from A sorority. It happens.