Most of the difference is down to currency variation and working conditions (e.g. most UK companies give 25-30 days holiday). If you benchmark it within countr

Most of the difference is down to currency variation and working conditions (e.g. most UK companies give 25-30 days holiday). If you benchmark it within country by comparing the ratio median dev salary/median salary there's not a huge difference between the US and UK (the US is a bit higher by about 10% IIRC) - although SF is higher.