When you record vocals you record 2-3 takes that are all heard simultaneously. Then, add on top of that, 4 vocal harmony tracks.
Can you imagine what that would sound like without processing? 7 people trying to hold a perfect chord. It's impossible. All harmonies and dubs are tuned to not garble the mix. It doesn't matter what genre we're talking about, any pro recording will have tuner applied to the dubs and harmonies, if albeit varying degrees of it.
Some examples where it is really apparent: Bad Religion. You've all heard those "aaahs" in the background. You think those would sound that "steady" if not tuned? They wouldn't.
If you know what to listen for, you'll find this in everything from Celine Dion to In Flames. Sorry guys, whoever thought tuning was just for T-Pain, I hate to break it to you: It's a required ingredient of pro recording.