You can transpose any song to any key of course but there is a ground reality that is middle C is at 260 Hz. The whole band can be out-of-tune, but in tune between themselves.
From https://en.wikipedia.org/wiki/Concert_pitch :
> For example, a 1740 tuning fork associated with Handel is pitched at A = 422.5 Hz, while a specimen from 1780 is pitched at A = 409 Hz, about a quarter-tone lower. A tuning fork that belonged to Ludwig van Beethoven around 1800, now in the British Library, is pitched at A = 455.4 Hz, well over a half-tone higher.
Besides the chosen pitch, only in an equal-temperament tuning can a piece of music be transposed to a different key and sound identical. Under different tunings, the ratio between subsequent notes is not always constant so transposing a piece of music to a different key will produce slightly different harmonic intervals.
Why John Frusciante is Out Of Tune (Scar Tissue): https://www.youtube.com/watch?v=Daw93bRHe4Y