Americans need bullshit the way koala bears need eucalyptus leaves. They've become totally addicted to it. They get so much of it back home that they can't survive without it.
'Haunted by the past' is a commonplace phrase because it's a commonplace experience. Even if one is not, strictly speaking, 'haunted', the past is perpetually with one in the present, and the longer it grows and the further it recedes the stronger its presence seems to become.