Sorry, I should have said "I presume you would never...". Honestly didn't mean it to come off that way.
> it would be no different for any of those professions
Do you want a surgeon with 12 years of experience or 3?
The issue at hand, unequal pay, has nothing to with experience in the first place, so making up an imaginary scenario where the experienced employee is a slacker is a strawman fallacy anyway. The point is that if someone from a low pay area moves 50 miles in one direction they could suddenly be worth 2-3x as much to the company?
Additionally, most tech companies don't actually pay based on cost of living, they pay based off of cost of the local competition. There are generally* 3 pay tiers in the United States; Hawaii is a Tier 3 state (lowest pay) despite being one of the most expensive places to live. The most expensive zip code in the USA is in Florida, but again: it's a Tier 3.
Anything above the cost of living is money the employee can choose to spend on quality-of-life improvements that are generally the same price no matter where in the USA you live (think investments, tuition, cars, boats, shopping, etc). The Tier 1 employee gets more money for those fixed-price items than the Tier 3.
I'm just saying it doesn't make sense; it's an artificial constraint made even worse when companies exploit the timezones of an employee because they desire a globally diverse workforce.
* Note: I only have experience with two businesses that collect salaries from mid to large (100+ employees) business subscribers in exchange for information about what others in their sector pay their own employees on average. It's a legal form of wage fixing.