It's a little hard to compare CTRs on content network IMO. Google has to account for CTR on per-placement basis but you don't see that granularity looking at aggregate adgroup data. For example, .04% might be great for a content text ad at the bottom of myspace profiles because competition has shown that that placement never gets clicks regardless of advertiser. In the same way, a prominent adsense block above the fold may require a much better CTR even on the same domain to get any inventory.
Once you account for the fact that this issue is even more prominent across different website designs and adsense publishers then you can see that the math gets really really fuzzy.
Not doubting you know your shit dullspace, but I'm going to have to respectfully disagree here(though I wouldn't say my mind is closed to what you're saying)
When I look at the fact we have limits on the number of adgroups, keywords, and campaigns we can have, I see it as Google's way of essentially limiting the processing power we force them to use. While they do have an ungodly amount of power at their disposal, they know better than anyone that speed is important(that's why we have 10 results showing by default, not 20; they tested and decided the extra fraction of a second it took was signficant in terms of user experience).
Adwords CN is the same. Speed. To calculate the ad's individual CTR on each independent placement would be INSANELY wasteful. Especially since many pages get < 1 impressions per day.
Beyond that, the lag time before stats update, and lag time before campaign creation seems to me they're caching the data and not really using it on a rolling basis(but rather with an update every X minutes/hours).
They couldn't really cache the data on a per-placement basis for every ad on every page the keywords occur.
I could be wrong here. But it's just what seems most logical to me, and seems to hold true in my own campaigns. But it's a bit of a pain in the ass to effectively test the theory in any meaningful way
Edit: Perhaps this changes around a bit if the person is
targetting a specific placement?