It's different because it's publically viewed by everyone. I'm suggesting that even if this isn't checked...
...there should be a general moderator permission to view the results anyway.
Could be. But I think wrapping it as separate permission would be best so that you don't give everything to the moderator (or whomever), just the poll results privacy override.
Interestingly it no longer seems to tell a user when voting if it is a private poll or not (it used to in XF1). I don't know if this is by design or an oversight?
I suggest different levels of privacy for different user groups. One can be a mod in Forum A and another in Forum B (think social groups). Mod A shouldn't see Mod Bs votes in my opinion.
Ah apologies, it's fine on my site too, which also shows this. I thought it said something about votes being anonymous/private when "Display votes publicly" was unticked.