Slaves isn't the right word because they enter into that contract by will, though perhaps sometimes by necessity.
I'd say that the results for them are poor on the a large scale, but not necessarily noticeable on an individual scale because one of the biggest factors is uncompensated risk. If you don't lose your car while driving for Uber, no problem-- but a big problem if you do, which definitely happens sometimes.
Of course, this makes it sound like the Uber driver and AirBnb host are slaves of the big corporations.
In reality, drivers can select times when there is greater demand and thus, higher rates. AirBnb hosts can set their own rates, and are subject to market realities. In addition, either is able to sign up with a competitive services, e.g. Lyft or Homeaway.