Record companies service stations they think will play a song with the material that fits.Do the record companies "preclassify" songs released for radio, or is there a person or small group that does the classification?
Stations get lots more songs than they would ever play. At the station, they decide on each song. And the record company promoters try to sway the decisions.
I worked at a CHR that was the #1 rated station in our relatively small market; we were adjacent to a large market and also showed up in the numbers there. Reps and promoters were constantly hounding our station to play their music so they could report in R&R or Billboard or whatever publication that their artist(s) or song(s) were getting airplay. Our PD and MD at the time were masters at using that to their advantage. Again, we were a smaller market CHR, but we had a customized jingle package from Century 21 or JAM, an amazing sounding V/O guy did all our jock intros and positioning, our morning show guys had the best show prep service available at the time with access to fake callers, fake commercials, song parodies, comedy bits, etc., and we always had plenty of swag with our station's logo on it to hand out to listeners. Most all that stuff came to us because the PD and MD would work on the record reps and agree to play their music, but would explain our station's "needs", and they'd usually provide. This was especially true if there was a crap song that even the record reps knew wasn't great, but they were under pressure to sell it and get airplay.I was the music director at a rated station in the 1980s. We were a CHR. Easily we got over 100 songs a week sent to us and we even got a few that would come to the station with their release in hopes that might sway us. Since we reported to a couple of publications like Gavin, every Monday for a couple of hours or more, I fielded calls from reps from record companies and independent reps about listening to and asking for an 'add' to the playlist. There was an orchestrated effort to get enough stations any given week to add a song to get it to show as an up and coming tune in the trades. The record companies knew an up and comer would get folks to take a listen.