I like the transparency in theory. In practice I don't want my salary to be so easily determined by a quick web search. It could really inhibit my ability to negotiate a higher salary at my next job where they'll likely offer something like 5% higher than my current job. It's hard to justify a 50% pay increase.

I doubt most employers would hide that they're paying you less due to where you live. Instead I think most would bring it up in negotiations hoping to use it as a means of keeping your salary low. And honestly, the argument that your salary should be adjusted based on cost of living would work on a lot of employees even though it shouldn't.