Alberta has loads of extra, OFF PEAK, when EVs can charge. Warnings about PEAK time usage (4pm to 8pm) have nothing to do with off peak capacity.
It is like saying the highways are busy during rush hour, that means there is no capacity for a late night transit bus to run on the highways.
Think about this:
At these temperatures gas cars need to be plugged in to prevent lead acid starter batteries from freezing. (If people are really worried they could get a lithium based starter battery.). But if you get home at 4pm and don't plug in until 8pm as they advised, your car may not start the next day.
Plus who loves running out in the cold to plug in? ( EVs on the other hand can be plugged in and the charging set to start at a specific time.)
Another aspect is block heaters will use between 300 watts to 1200 watts, with a typical one drawing 600 watts. In these temperatures, a car should be plugged in continuously, when not driven. The average Albertan is 18km or 25 minutes one way. So for 23 hours a day they are commuting, let's add another hour for running errands, so 22 hours a day where the car needs to be plugged in at work or at home, where ever. 22 hours × 600 watts = 13.2 kWh.
The average EV uses 20 kWh per 100km in ideal conditions. Ignoring the fact that newer EVs are more efficient, factoring in EV heater usage for 2 hours of drive time at 2000 watts, that is 4 kWh for heating and say 42 km of driving, so 8.4 kWh, total usage per day at these temperatures is 12.4 kWh.
This means to charge an EV for a day's use will use less energy than to plug in a typical block heater for 22 hours a day. And EVs don't need to draw power during those critical hours between 4pm and 8pm when there is a power advisory.