"But then their images are so strong that pretty much any print of their negs banged out by a kid in his first 10 minutes in the darkroom will probably be decent!"
You obviously haven't seen his negatives. And the statement devalues those of who are professional printers. If your statement were true, Salgado would save himself a lot of money by finding the cheapest person he could to print his work. And it would probably be the local FNAC.
"With a good negative of a strong image in hand, making a "good" print is a piece of cake, fairly mechanical in fact."
Maybe you just haven't seen a good print then. Its hardly mechanical. Again if it was, and a professional printer wasn't involved in the process, I doubt photographers like Salgado would be selling prints for the amount they are...since they'd most likely look like snapshots.