A remote worker's "market" is the world, so you are competing with other remote companies, not other local-to-me companies.
We don't downsize your salary. But sometimes we can't upsize it. There's a few companies we can't compete with on salary like Google. Most of those employers seem to be in the bay area. Sometimes we lose out. A lot of times we don't. The world isn't quite so black and white here.
Jill can do better. Hopefully other remote companies seek out the Jills and pay them what they are worth.
My 2c: You don't have to accept the job offer if you don't like the salary. Hiring is a 2-way street, if the employee and employer aren't both happy with the salary package - then bail. Plain and simple.
Or pay rural/developing world employees more than they demand?
IMO, both are at least a little bit irresponsible.