The taxi industry pioneered the 'independent contractor' business model. Some of the services you suggest cross the line between 'contractor' and 'employee', especially 'healthcare subsidy'.
The owner/operator whom I drove for says that the company only provides liability insurance (to cover the cab company's liability) as a part of her contract with the cab company. If she wanted collision coverage, she had to buy that separately, because insurance == employment.
When I signed up I was told that I should buy my own worker's compensation policy, but I never did this.
Most people don't want 'on demand' employment, they want stability. Because of outsourcing and automation, the economy doesn't need as many workers anymore. Uber's business model is entirely dependent on this phenomenon.
Drivers -- taxi drivers, 'rideshare drivers', trucking drivers, etc -- would benefit from a union. Arizona is not a union-friendly state; I don't know if taxi drivers elsewhere have unions.