Well, you just implicitly made your own case for ethics, one of the strongest ones, IMO: any situation where there is a tradeoff between individual gain and communal loss, ethical thinking is required. If that tradeoff doesn't exist, like the win-win situations that can be encountered in many economic situations, ethics aren't required.
Therefore it's never "beneficial" to you as an individual to be ethical in any individual situation. It's only as the ethical decisions begin to pile up across society that we see clearly it is more beneficial in the aggregate if everyone co-operates than if everyone defects.
anigbrowl is just noting some common heuristics that generate similar ethical outcomes but using simpler logic.
Anyway, I think the reason people are going beyond legality to morality here is that Uber has established a pattern of behavior over time as an actor that doesn't follow the rules and does whatever it wants. It isn't accidental; they've exhausted their reserves of good faith.