Hackneys are under stricter control than private hire because hackneys ply for trade. You get whatever random cab happens to be going past you and sees you waving at them, or whichever random cab happens to be at the front of the rank. With private hire you go through a booking system, which records the booking, the driver, and the passenger, even if that booking system is a single sole trader.
Personally, I'd go over to the Hong Kong system where every taxi is both a private hire and a hackney.
Biting the hand that feeds IT
