Every company has to take care of its own onboarding, so sure it's taken care of... for Uber and Lyft. But not for a new competing service. A new competitor has to figure the local regulations etc for every city they operate on, setup driver intake centers, man these offices, etc. New cities also typically suffer from rampant fraud and anti-competitive practices (e.g. subsidizing rides via VC money). Dealing with this stuff isn't cheap either.
> Uber and Lyft are pushing margins down because they want to extract profit to pass back to shareholders.
Profit comes from within those margins, so pushing it down (as in a race to the bottom) is at odds w/ shareholder yield. Also uber/lyft stocks don't yield in the first place (they haven't even had a single profitable quarter in the open markets yet...) In fact Uber/Lyft IPO stories have largely been told in terms of growth and market share.
> Delivering the cheaper ride for Uber/Lyft while also generating a profit means the driver needs to take a hit.
You can't really have your cake and eat it too. If you're delivering a cheaper price, then by definition driver pay goes down too. Uber can increase margins via economies of scale (e.g. the same call center can support US, Australia and India, price shopping for insurance on a per-month basis actually makes a difference, etc). The whole game is actually about getting as much market share possible to increase the total margin through sheer scale.
Having seen a financial breakdown of costs per ride, I can tell you that you are severely overestimating what percentage of a ride's money goes to things other than driver pay. The vast majority does indeed go to the driver already, and the rest gets extremely complicated on a city-by-city basis due to intense local competition, regulations, and a million other factors.
Overall, it really just sounds like you are armchair-postulating without any grasp whatsoever on the industry...