As long as I can remember it’s been this way, authors have always made very tiny percentage royalties on physical books. I don’t know what the figures are like for digital distribution but if they aren’t better it’s a travesty.
Well, Richard Bach writes in The Bridge Across Forever that royalties from Jonathan Livingston Seagull made him rich (before he overspent it), so I assume this is more recent phenomena. Granted it's a bit different level of "bestseller" though...