OK, yes, I understand the reality of using every measure possible to locate people for the reasons you note above. Personally, I think that is the real reason ERISA requires we mail these things out every year.
But, the real question is - after exhausting all measures, am I really required to store the hard copy as evidence? I would prefer to document the steps taken to locate the individual, then shred the hard copy. All of these boxes of paper are driving me crazy! And I would think the Fire Marshall would agree. However, storing boxes of paper for seven years vs. being tagged and possibly fined in an audit - I'll take the storage problem.