I have had this experience a lot in southern Utah, where I am out in the middle of BFE and have cell coverage. I never have it like this anywhere in California and not all that often in Arizona. It seems to be a Utah thing.
Best guess is that the telco made a deal with some powerful senator to get big tax breaks or something in exchange for actually providing service.
I'm 11 miles down a dirt road, in a wide canyon, quite a ways from Page, AZ, the nearest town. Not complaining, mind you, but I wish it were like this everywhere.