User responses to the pictures are not checked for correctness. Every time you see a reCAPTCHA, you can just enter a garbage value for the word that is less distorted and the system will accept it.

I'm suggesting that it's easier to detect text from these "mediocre at best" photos. Classifying objects in a visual space often deal with low quality images. In fact, the algorithms have to deal with the objects they're trying to classify at many different resolutions. While captchas are generally hard to identify even for humans, because they're contorted and confusing, the numbers in these addresses are all standardized numbers in grainy environments.

I would even go as far to argue that if these become widely used, we're going to see algorithmic "solvers" for this captcha in a matter of weeks.