I understand what you're saying, except a waitress runs the risk of losing her job for badmouthing the establishment.

An uber driver who answers me honestly when I ask how he likes the work runs the risk of a single less than 5 star rating, and no other consequences. That's part of the casual appeal of uber/lyft to a driver, I imagine.

What if you work for Uber, secretly. Just the sort of initiative Uber might undertake and I'm not exactly knocking this specific instance. Definitely an incentive not to answer in any method other than gushing love and gratitude.