"The Google AdWord Keyword Tool doesn’t show you how many people search Google for this term each month. It shows you how many AdWords ad impressions are available. And that includes Google’s search partners, content partners, and the entire AdSense content network."
Can you cite a source for this? Why would it say "searches" if it counts AdSense impressions?
The more likely point is that the number 1 ad or search result doesn't get 100% of search clicks, they are distributed among all results on the first page.
Just because a user might search for the terms every day doesn't mean it's necessarily even possible for them to convert more than once (like for a subscription service). On top of that a lot of searches are really just content-addressable bookmark lookups.
"searches" is some multiple of "customers searching"
"The Google AdWord Keyword Tool doesn’t show you how many people search Google for this term each month. It shows you how many AdWords ad impressions are available. And that includes Google’s search partners, content partners, and the entire AdSense content network."