They justify paying you less for the same work because of your location. So you are as qualified as someone else but make way less.
On the other side their products cost the same globally.
But now you have that info when applying to the job and it's up to you if you consider that fair or not. So far until now it was a (probably known) secret.
Information is power.
McDonalds will pay more in one town than another and sometimes pay varies depending on the location in town. They've done this for decades, and it has traditionally caused folks to take on a slightly longer commute to bring home a bit more extra money, but most folks don't because it still isn't a lot of pay.
The bigger point is that you know these things upfront. Want more money? Go ahead and live in the more expensive area.
And honestly, equal pay doesn't necessarily mean equality. Will both rates of pay give you a similar quality of life? Is it more fair that the person in Kentucky has a much higher quality of life than the person in New York?
Quality of Life isn't objective. People who choose to live in New York probably wouldn't have a better quality of life living in Kentucky and vice versa, even at the same pay, because so much of what defines quality of life for those people is tied up in the things that New York or Kentucky can uniquely offer.
Even between, say, Chicago and NYC is a huge difference if the salaries are equal (because housing prices are cheaper in Chicago, and the quality of cities isn't going to be so different).
But it's a huge step forward in information-equality.
I think this will even out over time as more workers are remote only. Once someone in Tulsa can do the same job as someone in San Francisco, and also easily find another similar job, I think the pay in Tulsa will go up and the pay in SF will go down.
Companies are already fighting this by saying, "you'll get paid $X if you live anywhere in the US, but you'll get an extra 20% if you come into the office in San Francisco every day". So now you have to choose how much that 20% is worth to you.
And you can know this thanks to the transparency and it help to make an informed choice. And if this policy prevent them from recruiting good worker, they will change it.
In a non transparent setup, they could be doing it a none would be wiser.
Fine by me. I'm happier in the middle of nowhere, anyway.