Just because they are numbered, doesn't make them primary.  I have driven down numbered dirt tracks to nowhere (admittedly not in Md.).  I would like to see the characterization of the roads represent what physically exists, rather than a database characteristic.

To Joseph's comment specifically, if there is  a non-obsolete classification hierarchy, please point me to it and I can update the OSM documentation.  Also, the descriptions I was quoting were mostly from the US specific descriptions in the Wiki.

This area is a mesh of roads without there being obvious direct routes between common destinations.  It is a boundary between suburban sprawl and old farms.  Many options exist to get you from A to B.

My aim is simply to make the map match the reality on the ground as as I reasonably can.  As it stands, there are glaring inconsistencies in the road classifications.