It's not "terrible coverage" that you're suffering from. It's the Laws of Physics, Jim.
In this case, radio propagation. The idea that coverage can be achieved in every single cubic centimetre of a city is Total Bollocks (tm) (1). With far fewer massive solid objects to reflect the waves and cause multipathing, you could perhaps get closer to that in rural areas. But there, of course, there aren't enough base stations and the issues become signal strength and line of sight rather than multipathing.
(1) Ob. Peter Cochrane - unless we'd put fibre into every home with NTEs that were also pico-cells.