Taxi medallions are hellishly expensive. Most of the time, you have a loan to purchase your medallion, that you then spend a long, long time paying off. It's essentially a form of indentured servitude. You can switch to Uber/Lyft. But you still have to pay off that loan for your medallion. And if Uber/Lyft aren't paying the same rate as driving a cab used to, you can find yourself without the money to pay your medallion loan and still make ends meet.

That said, I disagree with the headline blaming this on the gig economy. There's lots to blame the gig economy for, but this is pretty squarely showing the flaws in the old medallion system -- that you need a crippling amount of financial debt in your name to participate in the system.