Two comments.
Who's to say that this "common usage" issue does not exist in Virginia as well?
"Common usage" in Virginia
does separate the Separated Towns from counties--as affirmed in official highway maps, atlases and whatever else.
Perhaps this perceived "wonkyness" (laziness) concerning Ontario road maps is do to the fact that the purpose of said road maps has no use for defining such things. It just isn't information pertinent to navigation.
Funny; they were evidently deemed "pertinent" back when, well, the official Ontario road map was "pertinent", back in the pre-MapArt/pre-GPS 1960s and 1970s. And likewise, state highway maps and Rand McNally-type atlases--they always depicted counties (and Separated Cities, too, in Virginia's case). Maybe not strictly to
navigation; but certainly to giving one a feel of the geographical lay of the land--and to anybody who grew up throughly instilled within and conditioned by that mapping culture, to discard such county coordinates would have been a feat of disinterested idiocy on behalf of the kinds of schmucks who seldom stray from the I-75 en route to Florida.
However, your "just isn't information pertinent to navigation"
may help explain why the much more acutely navigation-focused universe of GPS has, for increasing numbers, displaced said maps and atlases--and why the overall trend's been toward the common-geographic illiteracy of Jonny5's friends and peers...
EDIT:...and maybe in that light, if it's
strictly a matter of navigation, it's better to let GPS be GPS rather than for maps to lamely, half-heartedly "respond" to the GPS age through letting such traditional mapping stuff as county coordinates go lax and flabby. In which case, the better thing might in fact be to
reaffirm the time-honoured county-boundary'n'stuff thing: a sort of gentrified afterlife for the traditional highway map. (Though that may be hard to come by or recapture in Ontario, given all the mega-amalgamations that make a hash out of all those traditional coordinates.)
