Would propose that a better relative measure of salaries is not against cost of living, but the delta between what it costs per year to hire a contractor vs. hi

Would propose that a better relative measure of salaries is not against cost of living, but the delta between what it costs per year to hire a contractor vs. hire employee for the same role. This would show whether firms are in fact paying more for employees against the contracting cost, which is the real clearing price for the value of the work in the market - unclouded by promises of "stability." Do we have anecdotes about the delta is between how much it costs to hire a contractor vs. employee for same role in the Bay Area vs. Toronto. In Toronto, anecdotally, per year a contractor costs between %175 and %200 of an employee. Contractor firms take their %15-%50 cut depending on contractor desperation. What's it like in the Bay Area?