It happened to me. The Uber app assured me that a driver was on the way, then it was late, then it canceled, and not a single driver was available within the area.
This was at 6a to catch an 8a flight in a Bay Area town that’s 35 min from SFO.
Uber and Lyft are now exactly like cab companies, the only difference being that their “credit card machine works”
Private car services work remarkably well if you’re done with Uber, Lyft, or taxis not showing up.