I know southwestern Ontario modestly well, having vacationed up there a couple of times in the last five years. What you have said is mostly true
but.
- Highway 8 is divided well past Kitchener and only reverts to a rural highway about 10-12 km before Stratford.
- There is continuous work being done on the 410 around Brampton, and Highway 10 north as far as Orangeville I would classify as a "super super non divided highway" (very wide four lane non divided highway with very broad shoulders and lots of space to avoid oncoming traffic).
- They have completed a bypass around Wasaga Beach and Collingwood (non divided to be sure, but a limited access "super two" with overpasses and I'm pretty sure a potential to be divided in the future)
There is no question that large towns like Owen Sound and Goderich have been ignored by the Ontario Department of Highways, but Ontario has more urgent business trying to keep highways in the Greater Golden Horseshoe from becoming hopelessly overburdened. It is always difficult to compare the needs of two entirely different provinces.
And finally, it bears repeating that the dividing of the southern portion of Route 11 here in NB isn't just to serve the pampered citizens of Bouctouche. Highway 11 is the principle highway connecting Moncton to the Miramichi, the Acadian Peninsula and the Chaleur coast. There is a lot of truck traffic, and south of Bouctouche, the traffic situation is compounded by exurban commuter flow and tourists traffic. Throw in weather conditions and moose and I think you have ample justification to divide this segment.