Well, it may be anecdotal and hyper-focused on "the new kid on the block" but there are plenty of items in the news these days about incidents with Uber drivers...
And I can tell you second hand (I have a couple friends or acquaintances who have passed the Uber X "checks") that it's a trivial process that almost never gets rejected. The taxi licensing process in the US isn't all *that* hard, but it's still a lot more strict - and government regulated and *public*, not controlled at the whim of a private company with a vested interest to hide problems and doesn't need to publish its process or data.
But I'm not even really knocking Uber's system, the original comment just asked: "Forget about questions of fairness, step back and look at first principles and evaluate whether the regulations are of value to society. Were these rules ever necessary? If so, why? Do the same reasons apply to Uber and Lyft?"
And I think the answer is, whatever method is used to check and enforce them, yes, taxi/rideshare/whatever regulations are absoluately a value to society and were (and still are) necessary (in some form).