Some factory head units put out 12v, so they can be used to drive speakers directly if you don't pay for the 'upgraded' sound system which includes an outboard amp (with speaker-level inputs). Monsoon systems in VW's seem to use this trick.

Many home audio CD players, especially semi-high-end ones, put out 1.2v or 2v so they sound 'louder.' Many of those have spec sheets that say "1v output".

That way, if you compare two CD players to each other in-store, you'll prefer the one that sounds louder, because you'll think you didn't touch the volume control. Psychoacoustic marketing 101.

A little sleazy? Isn't all marketing sleazy?