You fail to take into consideration the Uber and Lyft faced lawsuits in California by drivers over employment status. By complying with fingerprint background checks, corporate insurance, etc could lead to issues down the road.
The drivers will be replaced in the next few year by self driving cars. As a independent contractor you do not have the same rights and protections as an employee does. So imagine once these drivers are terminated with no notice, no severance, nothing they would ban together and sue.
By following cities ordinance could lead to a judge ruling against Uber and Lyft stating they were in fact employees. That would mean a major hit to their pocketbook! That is the true reason they spent almost $9 million fighting this.