> How's that a negative aspect?

Well, it reinforces a system where predominantly rich, white men who won the passport/work-permission lottery at birth are destined to continue receiving more money for doing the same work than the predominantly brown people of Asia and South America. It's difficult to understand why anyone who values equality would support this.

> you get paid the local rate and so can live anywhere in the world comfortably

You mean, what the company considers "comfortable", even though they don't live there?