[obmelvin]

The reviews are by and large free. I've known multiple phd candidates to be given papers by their advisor and they do the initial review for their advisor. Often these are additional reviews asked for by the advisor. That is to say, the advisor is usually not trying to avoid doing work, but they want their students to gain experience reviewing papers. Neither the advisor is paid for their individual reviews or supervised reviews, or is the student compensated in any way.

Amazon reviews are not remotely a good comparison. There is huge incentive in terms of experience gain, getting a bit of a sneak peek at research, and reputation gain(lets be real, its not that uncommon for people to be fairly confident they know who an anonymous reviewer etc is).

I'm not trying to make any point other than to add further disagreement to the idea that these reviews are not currently obtained essentially for free.