There's been some controversy that the new "Uber" freewheeling ride service (very prominent in DC and Baltimore Pride parades) will destroy the whole business model for taxixab service in some cities, especially Chicago, where the Medallion is an "investment", created, however, by government regulation, as explained in a Washington Post story Sunday my Emily Badger here. Medallion owners hire drivers; but the supply of Medallions is kept fixed as part of a city's regulatory scheme. If the model breaks down because of "disruptive technology", they could become worth much less than what was paid for them, that is, go upside down.
As for jobs, I actually looked at becoming a driver in Minneapolis back in 2003, for Green cabs. I found out you become an independent contractor, and pay about $400 a week for the cab; so it takes about 20 fare to make back the lease.
The new model seems to encourage a free-wheeling approach to giving people rides, although background checks are required, and cars have to be clean and in good order, and a lot of technology setup is required.
That's an idea I've already seen in calls for volunteerism. It can't be taken lightly.
There is an idea that unregulated taxi services leave a lot of customers stranded. I understand that the DC area does not use medallions, but is heavily regulated. I have found that it is hard to get a cab late at night on U Street (near the clubs), but not near Dupont Circle. But it's gotten a little better recently in the U Street area. The "Taxi for hire" sign helps.