This is true, but I don't think it's the literal adult responsibilities (or lack thereof) that make the difference.
Everything is new and exciting, McDonald's food is magical instead of cardboard. Our parents are perfect and know everything, instead of two more knuckleheads just trying to get by. The adult world from that perspective seems like it has order and logic to it (even if we realize we don't understand it at the time), rather than the reality that everyone is just winging it. And then are brains are hard-wired to latch onto the nostalgia for it all.