And I suppose you have to apply "collaborate" in proper context. If you mean "everybody works on it together" that is one context, but that doesn't equal "everybody wrote it". The Motown band I was in did a handful of originals that I wrote, and while I said "Okay axe man, here's 8 bars for you to do with as you please" and the tenor player/vocalist was free to embellish, it was still my song and there was never a question about it.

There is no better feeling for me than when you slip in a song and introduce it only as "Here's one you have not heard until tonight" and nobody knows it's original until you finish. AND nobody has left the dance floor. Right after that up tune I said "This one's called 'Mirage' " and hit the sequencer start button. It was a ballad, and the floor filled up even more. After the set we had people asking where they could buy our CD (which of course did not exist with only 4 songs ready for it).

Now one day at rehearsal, the guitar player was noodling around with some chords and I said "Keep doing that", and put a clavinet part behind it. The drummer hit record on the 4 track and we made a copy of the vamp. I took that home and wrote a melody and lyrics. At the next rehearsal we ran what I wrote, the guitar guy added a bridge and a key change after the solo, and we ran it to 4 track and played it the next night. I considered that a group collaboration and we announced it that way. "Here's a new one called Not This Time". Wish I still had that tape, but there's been a lot of chicken wings and celery (with blue cheese) since then....