This is the one big exception. Under the ADA, service animals (like guide dogs for the blind) are always allowed, no questions asked, and with zero fees. An Uber driver cannot deny you a ride because of a service animal.
It’s not a matter of being “cool” or “nice”—it’s the law. So if you see a service dog in an Uber, understand that driver is following a legal requirement, not just being friendly. Pretty fascinating how that works, right?