We have had similar forum discussions. It's not logical to expect musicians to play music the same way each time. There's live versions and studio versions (some which can't be reproduced on tour). Electric vs. acoustic. Genre-tinted versions. Re-masters, re-releases and anniversary versions. New group members and different instruments bring variation too.

Then there are those who have a long career. D'ya think Chuck Berry plays his first tunes the same way 60 years after?

After all is said and done, there's improvisation... :D