I am not sure of the magnitude of wow and flutter on tapes, but the amateur modes definitely account for some frequency shift -- for HF, the ionosphere can shif

I am not sure of the magnitude of wow and flutter on tapes, but the amateur modes definitely account for some frequency shift -- for HF, the ionosphere can shift the frequency randomly (I kind of thought I was making this up, but found some papers on it: https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2009RS004210 https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/200...), and radio local oscillators are not perfect (usually temperature dependent). (For other modes like airplane scatter, meteor scatter, EME, satellite, etc. there is even more doppler shift.)