It's ok to listen to an embarrassing audiobook in the car where nobody else can hear. Also ok to gossip about other people, have a loud cell phone conversation, and honk loudly at the grandmother crossing the road too slowly. Cars are private space. Except when they're not.
Uberpool is a car ride with strangers. Strangers typically make a space feel public. And so it becomes awkward to do some of the things that are perfectly ok when driving with friends and family. Furthermore, violators are weeded out through bad reviews.
How does this change driving? Do cars become more respectful of pedestrians? Does the city get more quiet? Do homes get less violent because people are less likely to return home in a rage?
On the contrary, do trips get slower? Do people feel less comfortable riding across town in their sweatpants? And are drivers fired simply because they don't have a good grasp of social norms?
Perhaps all of the above.