Most of the Canada->SV difference is nuisance costs of adjusting to a different country. Immigration. A driver's license. Banks. Income taxes. Insurance. All the little things which we know how to do because we've done them all our lives but which are never really documented.
If I spent 5 years living in the bay area, that $20k/year would drop significantly, since I would no longer need to learn those quotidian details.
Perhaps I should have said that I consider Canada to be $5k/year preferable to silicon valley, plus $15k/year as a frictional cost of changing countries.