Most music isn't recorded live. Most instruments are recorded individually in mono, either because they are mono (e.g., and electric guitar, keyboard) or because they are rigged with a mic (e.g., drums). The stereo effect then gets added in the mix.
Hmm right. What about movies though? Those would sound super great, wouldn't they?
Edit: Or wait, they record sounds for movies individually too, most of the sound you hear is not there "live" or something... Or at least I think I saw that in some making-of once.
