That's because it is a double standard. However, people in low labour cost countries have usually preferred to get something rather than nothing, and they held virtually no power. People in low labour cost countries would need to collectively unionise/strike/fight for their rights, in countries that don't always have the best human rights laws, much less political will to defend their citizens. And if they win? Well, they might get those big companies to leave, because some other country makes it cheaper, or if they have to pay the same as back home, why not move the business back home?

People who are capable of working remotely from low CoL areas/countries are, in contrast, more empowered. Generally better educated, often English-speaking, sometimes fairly well-connected. And it's just as easy to work for <CoL-Adjusting company #1> as it is to work for <CoL-uncaring company #1>.

We're seeing a lot of people who thoroughly enjoyed full-remote work during COVID make it a dealbreaker to work remotely now. Those people often don't even consider on-site positions. This whole CoL-adjusted thing will depend on whether a good % of those people will consider CoL-adjustments a dealbreaker or not. I suspect some might, but not enough that it'll change the balance sheet, and so we'll see larger companies who can "afford" the bureaucracy of CoL-adjustment do it, whereas other companies will use CoL-neutrality as (one of the) carrots to attract talent from CoL-adjusters.