Do income levels play a role in the number of SPs in any given city? Yes and no.
Calgary does have a large number of professionals and high-income earners, but that also includes women. It's a given that a majority of SPs are from "the other side of the tracks" (so to speak) who choose life as an SP over slaving away at a McJob. It seems that Cowtown has more professional opportunities available for women than other cities. Most of the other major Canadian cities have way more low-income families than Calgary, especially Vancouver, Edmonton and Toronto. So that's why you guys have fewer local SPs to choose from, and most of them move from other places or tend to be temporary visitors. I'm betting that most of the SWs are shipped in from elsewhere.
Also, as it's been stated many times, Calgary is a conservative city, and the local authorities reflect that mind-set with repressive bylaws and more vigilant crackdowns on the SP trade.