It was a survey of the SBR Database. I know Bet365 benefited from some free accts given to a focus group a while back. But I can't explain Canbet doing so poorly. They would be my top pick for bases even over Pinnacle. New players do complain about the frame software and lack of a bonus. Not opinions I share.
In the big scheme of things it was a small sample and keep in mind the players in the SBR DB are a mix of sharps, squares and outright newbies.