In that website, I found this phrase interesting: "tend to fall within the ranges indicated below." At various gig websites like Fivrr and Craigslist, the going rate for editing services is about a third what is listed here.
Of course, if an editor thinks she is worth ten times these rates, I'm sure that she is. The site does specify that rates are based upon a survey of members. It's useful information.
It's just surprising to me that there exists such a huge discontent between the rates that editors claim they charge on one side and what is being advertised to customers on the other. I wonder if there's a specific explanation for this variation or if it's a matter of two swimmers diving into different ends.of the same pool.