> The new companies, unlike taxi operators, have lesser insurance requirements, no restrictions on the number of vehicles they put on the streets, no clean-air standards and less-stringent background checks.

There are clean air standards for taxis? I'm not sure how well they work, since about half of the taxis I have taken recently (worldwide) have had the engine light on, indicating a likely emissions problem. Since taxis drive so much, an emissions issue on a taxi for a month is probably equivalent to a year on many private vehicles.

That said, even private vehicles have clean-air standards in any state (like mine) with emissions inspection requirements.