People travel distances that would be unimaginable for some of us to get to work. 30-40 miles one way is not terribly rare. Or they spend the week living at the job site, and go home for the weekends.
I'm not sure 30-40 miles one way is terribly unusual even in relatively urbanized coastal areas :-) But I agree with your basic point. I'm not personally familiar with how shifts typically work with oil drilling on land, but when I was working in the offshore drilling industry it was week-on/week-off in the Gulf and many of the workers came significant distances--often from rural towns in Louisiana, Mississippi, or Alabama.
In the SF Bay area, lots of people regularly trek from South Bay to work in SF - often between 60+ - 30 miles each way. Whenever I need to go into the city, it's 55miles each way. Fortunately I don't have to do it daily but it sucks when I do as its almost always rushhour.