That's because it is fake and nothing more than two mono channels.

True stereo is something entirely different. It's a recreation of the space sounds generate in the real world naturally.

A real acoustic guitar played does not produce two separate waveforms that go to each ear. It's the world around us that makes the sound stereo. Waveforms bouncing of every object insight, your head space, the distance between your ears as well as the speed it travels at. Your brain even has the ability to detect where a sound is coming from in a 360 degree space even though have only two points (two ears) listening in a 3 dimensional world. That's pretty amazing as you normally need 3 points.

For example, if someone says something while standing behind you. Why do you think you can hear that they are behind you when the sound comes to your ears equally and at the same time?

The answer to that is complex but ultimately it proves the point that mono is not natural to the world we live and that stereo is.

Regards
James

PS... that reminds me, I have a mp3 file I must upload for people to play around with. Form listening on only a pair of headphones you can hear sound in a 360X360 direction.