The cost of life argument makes no sense. By this logic we should be seeing janitors, or translators, or piano teachers in SV being paid much, much more then they are. If there was a coal mine near San Francisco I suppose the miners would be paid 100k/year as well?
Glassdoor says that a janitorial salary has a national average of $21,060; compared with $31,200 in San Francisco & San Jose CA; and $24,000 in Wichita KS.
Since the average starting salary of a coal miner is $60-70k in the rural geographies where coal is mined, I'd say that yes, a coal mine in San Francisco would likely pay $100k.
And for experienced pit deputies in the UK the going rate for a single 12 hour shift in a deep coal mine at the weekend was £2K and that does count towards your final salary pension
Probably closer to $75K? If coal miner had a choice (most don't) of whether to work in Ohio for $50k or SF for $75k, I'm assuming they'd pick Ohio.
Thats why someone wouldn't start a coal mine near SF.
People are only going to be paid up to the point where a company still makes money from them. This has a high ceiling for software devs, a low ceiling for janitors.
It's typically partly removed from your salary: you join a corporate health-insurance plan, whose premiums are partly but not fully subsidized by the company, with the remaining $x/month after subsidies coming from your paycheck. Some googling suggests that the average employee's share of the premium is $1100/yr for single people, and $5300/yr for those with dependent families. The actual numbers vary (quite a bit) by location and company.
It's a little of both. If your employer doesn't cover 100% of the premium then your share is deducted from your pre-tax salary. Healthcare is often one of the factors up for negotiation in salary discussions. It's not a 1-to-1 ratio, but generally if you opt out of an employer's coverage you can try to use that to ask for a higher salary. I've found it's been far more successful the older I get! The reason is employers want young healthy people in their insurance census (young people are cheap to insure and lower the cost for everyone), not middle-aged people with kids.