One of the issues here is about Uber getting away with paying the same type of taxes than other businesses, which creates an unfair situations with other companies & a race to the bottom for workers rights.
"Workers rights" are things like the right not to be refused a job because you're a woman. I don't think anybody is accusing Uber of doing this, nor would doing it give anyone any apparent competitive advantage in modern markets.
Classifying things like unemployment insurance under that banner is silly, because anybody who wants it can go buy it with money, so it makes no sense to require it rather than letting workers and companies negotiate over whether they'd rather have that or some other thing like higher pay. Every company has to convince their workers to work there and not somewhere else, so everything like that which they don't provide requires them to provide something else instead.
Imposing those requirements hurt workers by taking their options away -- somebody who knows they're only going to be a driver for four years as they work their way through college may very well be better off to have the money that would otherwise be paid to the insurance carrier than to have the unemployment insurance, which they'll not use anyway because Uber doesn't do "layoffs" of contractors and it's very unlikely demand for rides is going to disappear in the next four years.
Sounds like a bug with the tax law to me. Maybe there should be a services tax which is used to fund benefits, or something of that nature? Not a fully considered suggestion, just pointing out that this isn't obviously a fault with uber rather than the way taxes are structured.