a big part of the whole "hack" of Uber in the first place is that people are using their personal vehicles. So the depreciation and many of the running costs are sunk costs already. Once you paid those already it becomes a super good deal to make money from the "free" asset you already own.
The depreciation would be amortized to cover more than one person. I only travel once or twice per week, it cost me less to use an Uber than to own a car.
When LLM use approaches this number, running one locally would be, yes. What you and other commentator seem to miss is, "Uber" is a stand-in for Cloud-based LLMs: Someone else builds and owns those servers, runs the LLMs, pays the electricity bills... while its users find it "economical" to rent it.
(btw, taxis are considered economical in parts of the world where owning cars is a luxury)