Human memory is very unreliable. Everytime you recall something it gets changed ever so slightly and written back with the changes.
This is why two people can have completely different versions of the same event and why police use notebooks.
Playing music is the same as telling stories. Everytime you play something, an embellishment creeps in, another member will adjust to the embellishment, another member will adjust to that adjustment.
Any covers band who says they play it exactly as the original are deluding themselves unless they're regularly referring back to the original.
I've had issues when practicing at home and finding the song completely different to what we play, at that point there is no point in referring to the original recording other than for V,C,M structure and chord progressions. Even bass lines will have changed to create an arrangement that works with our instrumentation.
We play a lot of pop that has strings, brass, synth, piano, orchestra, drum machines etc. We have Drums, bass and guitar.