I think it's very clear that a human driving a normal vehicle is different from a human sitting at the wheel of a self-driving (semi-self-driving?) vehicle. You simply cannot expect a human to remain as engaged and attentive in such a passive situation.
It's baffling to me that they chose to deactivate emergency braking without substituting a driver alert. If the false-positives are so frequent as to render the alert useless (i.e. it's going off all the time and you ignore it) I don't think these vehicles are suitable for on-road testing.
You can lean fairly heavily on the 'still dangerous, but better' argument in the face of 40,000 US vehicle fatalities each year, but there are limits.
It seems that Uber wasn't actually verifying that, though.
Nobody disagrees with you and that is explicitly the reason why a human is on board, so I am not sure what you are arguing against.