People don’t use Uber because they’re a monopoly. They use it because it’s convenient, it’s a known quantity, it’s mostly predictable, and they can use it almost anywhere they go.
People like to complain about Uber, but my pre-Uber experience with taxi services was far worse. The hypothetical case of Andy’s small town taxi service that provides exemplary service either didn’t exist or was such an outlier that you couldn’t reliably find it while traveling.