Record sales accounts have always been shady. It benefits the record companies. When Berry Gordy was running it, Motown never even reported sales to the RIAA, and they and other labels had 2 sets of books, one for themselves, and one they would show the performers who asked to see them (which had lower numbers.) Then records sold though clubs like Columbia House (the old 12 albums for a penny, lol) aren't counted as "sales". Also there are "cutouts" which aren't counted either. James Brown has said a lot of his records was selling better than what was in the top 10, but his label King didn't report the sales so he didn't get the positions (or money). Some labels reported fake numbers to get higher chart postitions. Soundscan didn't exist before the 1990s and even with that, mom and pop stores don't have Soundscan equipment, so anything they sell doesn't count. Then there's imitation "street" bootlegs. The artist has never really benefited, only the "suits".