So what if rideshare companies puts you under water if you are not working 40hr week just like an employee? Given the almost duopoly, wouldn't there is no recourse for workers but to accept the same terms as employees.

The essence of contractor model is that your future offers are based on past work, not past declines. If you as a driver were giving quality ride and decided to take 6 months break, there shall be no impact on your rating.