The Netherlands tried the experiment to, from one day to another, just remove almost all requirements to operate a taxi. Basically, the only requirements were that you had to have a vehicle that passes inspection, a valid drivers license, and register with the city government that you operate a taxi.
In Amsterdam, the result was absolute chaos. Ignoring for the moment the unhappy existing taxi drivers and companies (that was complete mess, way beyond what the police were able to control), many new entrants behaved less than professional. I.e., competing aggressively for the lucrative rides, being poorly equipped to actually deliver a taxi services.
The situation got so bad, that the old taxi company that everybody hated, was now suddenly was the most reliable taxi service.
The question then becomes how you view the taxi market. Is it a market where anything goes. Where sometimes, in the middle of the night, there is just no taxi that wants to take you (home) for a price you can afford. Where taxi drivers claim that tourists agreed to pay an insane amount of money per person for a short ride from the airport to a nearby hotel.
Or do you want something that is mostly predictable. Maybe not very efficient, certainly not nice. But with reasonable expectation that if you order a taxi, one will show up and take you where you need to go?