Taxi drivers risk losing the difference between what they can earn working as a taxi driver and what they can earn on ride sharing apps. It's probably a fair drop but hardly all of their income.
https://www.bostonglobe.com/ideas/2015/08/05/what-about-taxi...
So they potentially have a lot to lose...
Oh and all the regulation should be the same for taxi vs ridesharing like insurance requirements (commercial insurance is much higher which taxis are required to carry) and inspection requirements etc.