I don't think it's possible to meaningfully take salaries into account unless they also have a database with salaries for each profession. In my opinion, it's much better to leave that adjustment to the user.

E.g. if you compare median salaries in San Francisco and Tokyo, you might get similar numbers. But if you're an ESL teacher, you might get paid quite a bit more in Tokyo, whereas if you're a software engineer you'll get paid a lot more in SF.