It's like the T&Cs on something like Amazon, di you actually read them before clicking yes?
Those used to working on military contracts know through long experience the relevant manuals and specifications for military work. You throw in a team used to working on civil projects who equally just know the civil specifications, are they going to spend months trying to read every book/standard in the contract?
Assumption? Someone in a hurry just assumed the specs were the same, nobody had the military contract background to query the design - and it came back to bite them.