Amazon and eBay and margins

This is a post with questions but no answers. Just warning you up front. I was thinking about Amazon's results from last week, and wondering why it still seems to be the case that for all that revenue they still can't seem to scrape any real margin out of the business - $2.14 billion revenues last quarter worked out at $47 million operating profits or a margin of just 2.2%. When asked the straight question about profit growth by analysts, Amazon management ducked the question: from SeekingAlpha,

'CFO Tom Szkutak said "It is still very, very early for us. We think certainly from a return perspective, certainly we're looking at it over the long term". Another analyst asked how the digital distribution of music and video would impact Amazon's margins, and received this answer: "It's very early and certainly difficult to predict what will happen over time".'

Then eBay - a margin over 22%, down from the high of 35% they've managed a couple of quarters over the past three years, but ten times what Amazon margins. Here's the quaterly chart for the past few years.

But eBay also gives us numbers for Gross Merchandise Volume, the total value of everything transacated over eBay for the period. Last quarter for example it was $13 billion. See the chart below for what happens when you compare Amazon's margin on goods sold to eBay's margin on GMV.

I'm not even sure it means anything much. I'm not sure what the significance of it is. But something about Amazon calling as revenues the value of every book they happen to sell, when the publisher has taken most of the profit out of the equation already, made me wonder how eBay was able to make such substantially greater margins on what is fundamentally the same business model and come to the conclusion that the valid comparison between Amazon's revenues and eBay's would be with what eBay calls GMV, not what eBay calls revenues.