Now, I'd like to be ethical. I want to choose to be. And I'd like us all to be ethical to each other. But you should make the case that it's beneficial for people to be ethical to each other because XYZ, not because they have a "responsibility" to do so, or that they're "half-alive" if they don't. And to say that ethics -- a massive topic that has flummoxed philosophers for thousands of years -- is easy, is just wishful thinking.
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.
The simple question 'would I be pissed off if I were on the other side of this situation?' will get you halfway home in almost every case. It is your responsibility as a sentient being to make moral decisions, otherwise you're just half alive.