The value you bring to the company is almost irrelevant. It's all supply and demand. Of course if you bring a lot of value that might increase demand for you, especially if few are able to provide that amount of value.

Also, no market is perfect. There are (well-paid) employees that bring zero or even negative value without anyone noticing.

Theoretically the value you bring should always be higher than what you're paid, since it would be uneconomical to employ you otherwise. That said your second paragraph is absolutely right, there are plenty of failures. In a modern bigcorp I'd be willing to wager that value is created on a bell curve relative to a given salary level (so for example if you take a bunch of people making $60,000 in the same company, some produce no value or negative value, some produce moderate value, some produce extreme value). If I had to guess complexity actually allows the information asymmetries to flourish, so the market is probably extremely distorted and that's why you see the effect.

Right - a cleaner brings massive value (no one will work in an insanitary environment, so they in a sense underpin all work) but seeing as the labour pool is large, cleaners don't get paid a lot of money.

Everybody was so sure that working from home in a low cost of living region with SF salaries was going to make them rich. The few voices who warned that it also meant a bigger pool of potential employees with lower salary demands were ignored.

And so the cycle continues.

This doesn't sound right. Google gets millions of applicants per year. Surely some of those appliacants would be willing to work for less.

They don't get millions of good applicants that are willing to live in SV and work for less.