Verizon employees don't get any different commission from one phone to the other, they get commission on the contract. I just asked a manager friend who works there (You'll have to read through the english, he's drunk and at a baseball game right now):
Two Verizon employees told me that. I think they should know. I'll go with their info.
There was also a big story on it on one of the big tech sites a month or so back in a story about why Android phones are outselling the iPhone 4 on Verizon. The article specifically mentioned $50 versus $5.
It's a definite fact that this is what is happening.