Disclaimer: Consult a legal professional.
But from my understanding, the three different organizations represent different artists, and that’s why they want you to purchase their license, just in case you play the music they cover.
However if you are playing public radio or television in that size establishment, you don’t need any of them. I believe it’s under 2000 sq ft for any business, and anything over that they can limit the number of speakers – something along those lines. I’m not sure if that’s national, by state, or how it works.
But I’m pretty sure public radio is fine. If you are using CDs, MP3s, or streaming (like Pandora) then you need to purchase all of the licenses to cover all the copyrights.
In fact I’ve heard some restaurant chains pay to sing Happy Birthday since it is considered a public performance of the song, which is copyrighted.
I would join BMI…any songs played under their name…they are entitled to royalties, especially if you have been contact by them.
Also, you may have to attain ond from SESAC as well.
BMI Customer Service: 800-925-8451
Licensing Assistance: 888-689-5264
10 Music Square East
Nashville, TN 37203
*(Licenses are cheaper than attorney fees, fines and penalties.)
I Hope This Helps!,