I think it's worth noting that the road classification hierarchy on the OSM Wiki is obsolete, at least in the US and excluding trunk and motorway classifications. The definitions appear to be very European-oriented, since the bulk of the major roads in Europe were built on historic roads that connected directly between other villages, farms, POIs, etc, whereas in the US, that scheme is prevalent, but a lot of the country was planned out rather than built through time and has repurposed these roads as arterial roads or has built entirely new roads that simply intend to connect other roads rather than populated places.

These roads (Seneca, River, and Esworthy) at one point most likely connected between some hamlets at some point, but now serve as links between other distant towns (like Poolesville and Bethesda) or work as collector/arterial roads that serve Travilah and Potomac. Primary might be overkill, but I certainly think that there should be an established route through the area that indicates these roads are part of a direct connection between places like Poolesville, Travilah, Potomac, Bethesda, and DC that doesn't jump between two classifications spontaneously.