I offer a few more corrections, from my experience, which includes driving a Tesla for four years and metering the electricity at home for two:
1. The electricity price at home off peak is probably not 10% of the gasoline price. For the Model S it seems in the 20% range if gasoline is at about $1.30 and you compare to a gasoline car of similar size.
2. The loss going from AC to the car isn't likely near 20%. Comparing my metering to what the car indicates (again, an S), the loss varies a lot depending on conditions but seems to average 10%. The car doesn't indicate electricity use for anything but km, and that's an approximation. So 10% may not be right, but it's probably closer than 15%.
3. Some states allow SCh rates to go by the kWh but many do not. No province does, AFAIK, for the reasons Mike Knox has discussed.
Kudos to the people trying to figure out what the true SCh electricity cost is in Ontario. It does seem different for the Model 3, which I haven't charged.