Today's productions are not a snapshot of a live performance 95% of the time (even "Live" CD's are tweaked a LOT). Parts are overdubbed, then punched-in to fix a spot, nudged in time, sound-replaced or re-amped, triple-tracked for fatness, stereo-widened, compressed for impact and volume, and then eq-ed to the max. It's all part of the illusion of creating a "performance".

The video/movie industry takes things MUCH more to an extreme - sometimes characters exist ONLY in the computer (a la Star Wars).

Autotune is simply one more way to make the sound better.

People who are terrible drivers shouldn't be allowed to drive either...but they do.