Jack, the wiki and help site don't agree with you. 

https://wiki.openstreetmap.org/wiki/Highways#Carriageways

https://help.openstreetmap.org/questions/5471/when-should-i-divide-a-simple-way-into-dual-carriageway-or-divided-road

If there's no physical barrier such as a curb or dirt strip in between lanes, then it's just a normal road. For example a u-turn could hypothetically be possible in an emergency even if it normally wouldn't be allowed: for all intents and purposes it's a non-divided highway. Maybe if we get to the point of mapping highway areas we can micromap road markings like this but until then it's simply not divided, there are no junctions.