I have to disagree with this. It's probably true that e-commerce checkout processes are less optimized on mobile than on desktop, but that doesn't have a huge bearing on ad rates.

The majority of all ad spending is for brand awareness campaigns, not direct response. That's why CPMs for TV spots are still higher than both desktop banners and mobile banners even though TV has no checkout process. The prices are driven by Coca-Cola's spending, not ShamWow's spending. Also, desktop banner CPMs have been going up lately because of the new agency trading desks like Cadreon, Vivaki, and Xaxis. They are helping brands finally buy more digital ads because it's a lot more complicated and fragmented than buying TV, radio, or print.

Also, mobile usage is exploding right now. It makes sense that prices would be low while supply is growing faster than demand. Over time, the usage will level off and the ad dollars will catch up. I think the CPMs then will be a much better judge of the effectiveness of mobile ads, and I think they will be driven by how well brands can engage with consumers through mobile devices.