I'd say 75% at least ask if I want to take Rock Creek Parkway (though yesterday, one got lost and took me to Virginia...) These are old guys who hang around the Kennedy Center/Watergate all day. I'd say it's flipped for ride-sharing services, where the driver almost always relies on the GPS (I take it Uber's GPS isn't very good--Waze suggests the correct route).
I've noticed this on multiple occasions: Uber has pretty terrible built-in GPS. It almost always has my drivers taking the larger/busier roads even though they are less direct and more congested than side streets. It's like when Google Maps gives you the three possible routes, Uber often picks the equivalent of that weird third route that makes no sense.