First of all, the payment is about seven dollar according to the article that is slightly above minimum wage. It may be below some states wage but it is clearly close.

What mechanical turk does allow companies (and individuals) to do however is to hire people for a very short term (a few seconds) for, literally, pennies.

And assuming that enough work was available we should expect the rate to increase since there will be less spam bots.

And at any rate it is better than the alternative of make work.