I don't see how they can expect most rides to be a 5* experience. Most hotels aren't 5* hotels. Most films aren't 5* films. What do they think drivers should be doing in order to deliver such an extraordinary experience every time?
People say if it's a normal ride you should give 5* (and I do because I don't want to cause the driver problems if it's been fine), but you don't award a functional hotel room 5*, or award a restaurant 3 Michelin stars because their food was ok.