Another question that is not clear.

Here's the image from the whitepaper:
https://gyazo.com/843418524494e99ae38c6c91776de773

So the whitepaper's writer claims that is is impossible to sign up as a worker @ CrowdFlower. Where did this claim come from?

I was able to register as a worker in 10 minutes. And in another 20 minutes I've made my first 0.04$.