Anything as long as it is not exploitative (I personally have no concerns over this regarding Uber but I certainly include it as a criterion) and does not invol

Anything as long as it is not exploitative (I personally have no concerns over this regarding Uber but I certainly include it as a criterion) and does not involve tipping. Tipping is described as an opportunity to "reward excellent service" but in reality it satisfies the parts of the brain that respond to being given the opportunity to temporarily act as a financial master over other human beings.