Actually, Alberta has a substantial centrist, centre left vote, especially in the two large cities,; just relatively recently, 2014, the left wing NDP won at the Provincial level and even today has a substantial presence in the state legislature.I've just a bystander but I noticed how Alberta and Saskatchewan went almost 100% Conservative. Remind me of Montana and Wyoming here.
There is though growing frustration, legitimately in my opinion, with the federal government built up over the Trudeau years, that may make it seem that Alberta is 100 percent conservative, except for 2 or 3 city ridings.