You should work for whatever you can negotiate; and you are worth what someone is willing to pay you.

That being said, in order to align with their values of transparency, they shared an algorithm that makes sense. It's not the only way to do it, but it's transparent and doesn't seem unreasonable.

Startups are about alignment to the big picture and long-term. I'd imagine that's why they don't change equity based on location. However, The free market being what it is, some will take it and others won't.