To be fair, when Calgary and Edmonton built their LRT systems in the early '80s, the population of both cities was some 500-600,000. That's smaller than any North American city that currently has LRT, including Kitchener-Waterloo which recently completed a small line (and theirs is more "Streetcar" than "light metro"). I can see how going "subway" might have seemed like an unnecessary expense for what were then small cities.
The cities have literally tripled, give or take, in population since that time. Even if the systems aren't perfect, we are fortunate that we got LRT when both cities were relatively small, because I wonder if we'd ever be able to get systems properly funded and started today. A lot of comparably sized US metros (KC, Cincinnati, Indianapolis, Nashville, Columbus, Vegas, etc) still don't have proper mass transit systems.