That's actually a really good point. I can sit at home and relax with what I think is a pretty decent pair of Shure headphones connected to a digital source and forget that such a level of fidelity, especially in the highs and the lows, was not something that people in the past could easily take for granted. It's entirely possible that whatever the band and the engineers heard at the time just wasn't all that revealing in that sub-50 Hz range.It's possible that upon playback they listened to a big pair of studio monitors cranked way up and just didn't really notice it enough to force another take.
Great point!
