I don't disagree that more resolution is needed, but we do need to start somewhere when it comes to what truly is rural.
For me, the occasional farm interspersed between single-family homes (or the occasional subdivision of single-family homes interspersed between farms, same deal), strip malls, and Boeing Field (or, in my case, Scott AFB) isn't it. That's merely the outskirts of town.
Alternatively, if you have any chance at all of being reached by anything other than a 50 kW AM radio station from a major city like KMOX, you're probably some semblance of urban.
Similarly, if you can have mail delivered to your street address and not merely a shared delivery point, you're probably some semblance of urban.
Densely urban? No, absolutely not.