If the iPhone was available on every carrier we would have real numbers.
Plus, we ARE comparing OSes so platform does not matter. Right now it iOS vs Droid. The fact that Apple has managed to push it on multiple devices should not count against them...just as keeping it in one carrier has hurt them.
I disagree with the notion that the real numbers are somehow not real, and the real "real numbers" are the result of a "shoulda, coulda, woulda" situation.
If the iPhone were available on every carrier their would be a lot more people using the iPhone. It's almost like its every carrier and every phone manufacturer vs Apple.
Don't get me wrong, if I were in contract at Sprint or Verizon I would be on Droid also.
I have invested money in applications (not a whole lot). Switching platforms would also mean finding new software and purchasing some of them.
It is certainly possible that 25% of all Android users are not getting an iPhone simply because of carrier. I find this really hard to believe though.
If it were just devices the iPhone would be out-selling each individual phone independently.