People buy condos built in the outskirts of town in droves, so it is not that the market cannot support it.
https://edmontonjournal.com/life/hom...es-in-edmonton
As stated, it is the landowners. Because the prices in general are lower, the returns are slimmer so developers would rather chase easy profits in other overheated markets. But it is by no means an profitable venture and on the flip side there is no penalty to land speculation and holding/flipping. The situation should improve somewhat once the tax on derelict/vacant lots kick in.
As for the bird poop situation at Churchill, people feed the birds there so it all boils down to the same old question on allowing homeless to take over.