for questions as such alexa defaults to the wikipedia entry. either a short summary or the full text. the problem using wiki as a source is the overwhelming majority of pages can be edited, changed by anyone at any time. there are volunteers with wiki who attempt to check everything not only for errors but for lack of citations, for offensive material, the whole nine yards so to speak. there just aren't enough volunteers to check the
25 Billion+ unique pages.
amazon using wiki as source material the problem. granted wiki is much better than it used to be but point being wikipedia unfortunately is not the Encyclopedia Britannica. that example a traditional source staffed by and created by informed professionals that checked, rechecked and triple checked everything. rather wiki is created by everyone, the well informed, the not so well informed. let alone idiots deliberately messing up entries for their own reasons.
alexa is simply the middleman for better or worse. FYI if you find incorrect information on wikipedia please do correct it for the benefit of all. it's really very simple to do.