Burden of Proof

I got to thinking about the reversal of the burden of proof in the Columbia disaster which forced the engineers to prove why the space shuttle was not safe to fly as opposed to why the space shuttle is safe to fly. If the burden of proof was also reversed in a similar manner during the Challenger mission, how could the same mistake be repeated in NASA? Wouldn't the managers realize that if they reversed the burden of proof for Challenger and the end result was a tragic disaster, that if the same procedure were followed for another space shuttle, the same results could possibly happen? This frustrates me because it is one thing to make a mistake and suffer the consequences. However, it is another thing to refrain from making any alterations after the first mistake and then eventually making the same exact mistake again.