I've got an idea. CAPTCHAs could be replaced with suitable items of work from Amazon's Mechanical Turk. It stands to reason that these can't be solved by current computer vision algos, or else they wouldn't be on Mechanical Turk in the first place(?), and the side benefit is that the site owner can collect the 5 cents or whatever the going rate is.
Not necessarily. Let's say a company has some computer vision problem that it needs to be solved with 99.5% accuracy. Let's say today's computers can solve it with 85% accuracy.
The computers can't solve the business need, but they are certainly right often enough to get some spam comments posted (because their cost of being wrong is zero.)
