Because rideshare carefully uses economic incentives to generate outcomes by market means, not by "enforcing" through the heavy hand that only the government understands.
A) it’s not clear the outcomes are desirable in the first place and b) why are market means better? The market is good at deriving efficient prices in certain circumstances but it really depends on whether the desired outcome aligns with efficient pricing. Personally the problem Uber solves is a nice app to hail the taxi with, which doesn’t appear to have anything to do with market effects, whereas the material effects of Uber mostly seem to be exploitation of employees.