Even if there aren't location-based salaries as such, there's a lot of "ROFL, we're not going to match your Facebook offer." I worked for someone who eventually ended up with very few California employees and, I believe, eventually closed their relatively small office there.

>Moving is easy

I disagree with this. If you have a relatively small number of possessions living by yourself in an apartment, maybe. But, as you say, with a partner and even kids with an established circle of friends—and maybe a house, is definitely not easy.