I guess this effectively makes them a
black market taxi. It's illegal to run a taxi without a license, and this has been controversial because the number of licenses has always been limited and artificially low.
Uber and Lyft thus were at first seen as a loophole in some places or actually banned in others, but once it was clear they weren't going away most municipalities legalized them with regulation. But that regulation probably restricts them to only taking rides and fares via the app. If they take non-app rides, that's an illegal black market taxi service no different than if any random person decided to do this.
In addition to the laughable waste of resources, I highly doubt this is even a particularly widespread "problem." It's easier to hail a normal taxi than an Uber/Lyft anyway if you didn't want to use an app for whatever reason.
