1) Amazon's lack of profits appears to be due to reinvestment back into the business, not because the margins are non-existent. If the margins weren't there, there would be no money to invest in R&D.
2) The author never comments on the issue of double taxing corporate profits. Is it really the spirit of the tax code that $1 in profits earned by a business should really yield $0.48 to the federal government? The best way to address the author's concern is to put the effective corporate tax rate (35% corp income + 20% dividend) more in line with capital gains rates.