I think a lot of these job postings would have a lot more success if they showed salary ranges, in fact that just applies to all job postings. Why apply for EU remote working (if living in the EU) when you can remote work for a US based company? The timezone is off but programmers should be able to work autonomously and independently.
There are still quite huge wage & cost of living differences, e.g. a Bulgarian programmer working remotely for a Danish, Norwegian, Swiss or English company will be getting several multiples of what they'd be able to get locally and still be in roughly the same time zone (which is important for some companies/individuals).
I am living in Berlin and work remotely for a west-coast Canadian company (9 hours time zone shift) and it is in many ways quite a sacrifice.