You don't need to think of any other term - 'greedy' is correct. London rates are London rates because the work is in London, with all the baggage that involves. Take a look at the job listings for non-London work.
- more senior, so they'd get paid relatively more anyways;
- exceptional, so they'd get paid relatively more anyways;
- working too many hours, which is never a good idea for knowledge workers, and doesn't last long.
Completely agree this is a major issue in many companies.
This said, I'd call it more a problem with how a given company works on-site (open plan offices) than an inherent advantage of remote work; in other words, it's incidental.
But then you can't easily convince anyone to abandon silly open spaces these days :)
http://www.designcurial.com/news/survey-reveals-open-plan-44...