The driver uses that money to pay for his own health insurance and retirement. Contrary to your post, Uber provided me with commercial vehicle insurance when I was driving for them.
That is the problem here. Employed work means sharing the duties of social security between company and employee. Uber moves their payments on your shoulders.
And that point is exactly what makes up Ubers' valuation. Ignoring the questionable ethics of that this should be reconsidered though because comparing to the technical value of their service they are requiring way too many engineers to deliver their services, which is a considerable risk if they grow any further.
There is no duty for a company to provide social security for contractors. Same way as an Uber contractor has no responsibility to drive a certain amount of time or at certain hours.
And that point is exactly what makes up Ubers' valuation. Ignoring the questionable ethics of that this should be reconsidered though because comparing to the technical value of their service they are requiring way too many engineers to deliver their services, which is a considerable risk if they grow any further.