SES = Socio-Economic-Status
Mixed SES groups benefit the lower income people significantly, but it's a balancing act. Having worked my life in affordable housing, the trick is to "scatter" affordable housing into developments to that we don't cluster low income families and so that low income housing blends completely into the community.
Honestly, Canadian cities weren't ready for the mass rush to urbanization of our populations. When we moved to Alberta in the early 80's, the population was 50% urban. Now we're over 80%. That's a dramatic shift in less than 40 years. It's meant that the city grew so fast that development plans got left behind and the desire for "country residential" housing drove sprawl that was created with little to no infrastructure to support it. Edmonton basically has one new road since 1983. Our traffic infrastructure is suited to 500K people and we have over 1M. Same for transit. Shopping developments have popped up to service regional neighbourhoods, but these are also infrastructure nightmares with poor ingress/egress and hap-hazard layouts. Several of these developments have traffic on main arteries blocked due to interior congestion during peak periods. Stupid.
We aren't facing the affordability nightmare that Toronto and Vancouver residents are. Thank god. The cooling of the oil business has helped that, and it looks like the energy industry might be approaching an equilibrium spot where it makes sense at $50/bbl oil - and that's actually good for the province.
If Canadians want to all live in two of our largest cities, and they want to have affordable rents and housing prices, they won't be able to raise their families in single family dwellings with a yard and a driveway and so on. They're going to have to rethink things. One thing we MUST do is create urban shared spaces. You don't need a yard for your kids to play in if we have parks and other common areas. Canadian cities are terrible for having these types of spaces because traditionally families had their own outdoor space. That's not the new reality. Shared park space is much more efficient, but it has to be created.
When I see the GTA has all these massive traffic headaches thanks to massive 6,8, 10 or more highways I have to wonder if mass transit can't solve a lot of those problems. I get why Edmonton and Calgary have crap transit, but the GTA has been a sprawling urban center for far longer and should have been investing heavily in road reduction.
It still amazes me that Canada, a nation with perhaps the most usable land mass on the planet, has a population that wants to all live in one of two relatively tiny spaces.