Typical of the undermathed professions* : they provide high and low salary numbers, but no median! This makes this salary guide vastly less useful than it could be.
Judging by the ranges, it's my guess that these are not extremes, but possibly 25/75 quartile marks.
The methodology isn't clear, so we don't know how the data were aggregated/culled, but it seems that +/- 3 SD data, at least, were stripped in creating these tables.
* This phrasing is an attempt at humor