>All the people I know at Amazon in Seattle consistently get home after 7pm most nights, and a handful of those people come in on the weekends for 10 to 12hrs to fix mundane bugs that aren't in need of immediate fixing.

I can't speak on everyone at the company, but the campus is basically empty at the times I leave at 7-8 (which isn't often and usually happens when I show up at 11-12). My own building is 95% cleared out by 6pm on a daily basis.

Not saying what you hear isn't true, but it's definitely appears to be the exception rather than the rule from my experience.