I would say Bethpage and Oakmont are on a par (no pun intended) with each other. I agree Bethpage seems unfair as it seems impossible to sometimes reach greens or get the ball to stop on them. Oakmont with it's 5ft breaks on a 2ft putt also borders on unfair. They're set up as US Open courses, hence the par 70 and consequently a couple of holes that would normally be par 5's to members.
But, I guess it's the same for everyone (or is it???), and many players will be happy for a chip and a putt and walk away with a par to hold their score together. Almost realistic in the sense that not many players in real US Opens break par for 72 holes!
By the way, I've managed -6 at Bethpage (God only knows how!) and -2 in the USGA Championship at Oakmont, probably my best rounds on those two courses.