Which part in particular are you referring to as "wildly speculative?"  Increased overhead/lax TI enforcement (due to budget constraints) is guaranteed if there are more cabs on the roads no increase in budget.  The expectation of increased customer fraud via taking the long road, shortchanging, etc. will only be further incentivized with more cabs but no more demand.  The same for violation of traffic laws as cabs in the zone will increase for the same number of fares via speeding, running lights/stop signs, etc. to be the first one to pick up.