Well, the navy used the same khakis and dungarees for decades, the same 1911 and M-14. In the last few years, though, we've changed guns and uniforms - oh, lord, have we blown money hand-over-fist on ill-advised, unthinking uniform changes... Reasonable question. No idea why, though. Most reasonable interpretation, but Timo's correct that it "t'ain't neccessarily so". And that's the sort of thing the Encyclopedia did all too often.