I'm from the Midwest myself (sort of, Joplin, MO is at the edge of the West and is culturally Southern). Never worked here, though, but I don't get the impression
insane hours are acceptable here. Have worked in the Boston area, roughly in the '80s, and D.C. area, roughly in the '90s. No insane hours either place, aside from some occasional, short term, customer driven projects, which are a very different thing.
As for your latter point ... don't know. When I was "junior" the talent shortage was dire. When I was "senior", I wouldn't put up with such things, but even in cases where I got recruited without having much of an idea of the workplace culture, I don't ever remember a "you should be thankful you are allowed to work here" attitude. Might have been luck of the draw, although in plenty of those places a failure to have hired someone like me at the time would have resulted in the company dying, so....
ADDED: D.C. might be a special case: The culture is overwhelmingly influenced by government contracting, and the government is loathe to pay overtime. And contractors tend to get paid by the billed hour, so unpaid overtime costs them money. And at least compared to Boston a decade earlier, the time you spent in the office was a greater factor in judging your performance.
