So for your hypothetical $50k/year worker, the tax burdens are pretty similar; BC+Canada sales taxes come to 12% which I believe is a bit higher than California's sales taxes, but of course the BC resident has government medical coverage.
Two important caveats however:
1. Depending on your income, BC is the lowest-tax or very close to the lowest-tax jurisdiction in Canada. Someone earning $50k in Quebec would pay around $13k of income taxes instead of $10k.
2. Salaries in Canada are vastly lower than San Francisco / Silicon Valley salaries.