"How much time do you have?"
It's a complicated system, one with two licence types. One type (standard) can be sold or transferred to other taxi drivers, whereas another type (ambassador) cannot.
Ambassador licence-holders have grumbled about being at a financial disadvantage because they're unable to rent their cars out to somebody else if they ever get sick or need a holiday.
Meanwhile Minnan-Wong said standard licences are often held by absentee owners who rent out their cabs to other drivers and have little incentive to ensure a quality ride for customers.
"If you sit behind the wheel of your taxi, you're going to make sure that it runs OK, that it's not going to be stinky, that's going to be better for everybody," said Minnan-Wong.
Under a new single-licence system the city wants to phase in, owners would have to get behind the wheel full-time, but they'd also be allowed to rent out the vehicle to another driver for a second shift. The standard licences which can currently trade for more than $300,000, would be grand-fathered out.
The city had a plan to phase in a new system by 2024 but earlier this year, a judge struck down that deadline. Council voted last week not to appeal the court's ruling.
Now the standard licences will only be retired if the licence is sold, if it's surrendered voluntarily or when its owner dies.
Minnan-Wong also wanted to look at rules to address the rise of the unregulated ride-sharing app Uber.
"They need to be regulated," Minnan-Wong said of Uber, citing safety and insurance concerns. "If we decide to licence [Uber], all these vested interests who've been trading in these plates ... they will see the value of these licenses go down. They are going to fight tooth and nail to stop it.
"If we were to put the customer first, reform would be easy."