I don't think all of the economic benefit stays in NYC even when you take a yellow cab. A significant share of NYC taxi medallions are owned by entities based outside the city. Marblegate Capital in Connecticut owns about 2,146 medallions—nearly 16% of all NYC taxi medallions. They make more profit off the medallion financing business than actually operating the taxis which is basically break-even AFAIK.
I wouldn't be surprised if that's somewhere on Zorhan's to-do list :)