The region also includes Canada, because games from this region are played in both Canada and USA. There is also French language options in some of these "USA/NTSC" games which proves that it's also Canadian game because only in Canada is French an official language. Some of these games are Mario & Luigi games for the DS. Why the USA flag, and why the USA name? It should read NA/NTSC and have half USA and Canada flag.
They’re talking about when selecting a region for a console when submitting a run. It’s called USA/NTSC to differentiate from JPN/NTSC, but yes, it should be renamed to NA/NTSC to be better indicative of Canada being included.
Not really a huge issue tbh. NTSC-U is completely appropriate (and I think we just flipped that into to USA/NTSC for clarity). I'm not against changing it to NA, but honestly as a Canadian, I don't really care at all, it's always been considered the "USA" version to me.
Splitting the flag on the region icon would just be silly though, both because it would just not look visually appealing (and with the size of the icon, it wouldn't even really be clear what's going on) and because USA and Canada aren't the only two countries covered by NTSC-U.