I'd also add: 5) engineers often totally forget about the black swans (or unknown unknowns) - especially obscure edge-cases that require special handling.

I'm not sure that's what is meant by a black swan, but in any case, this would be a factor only if managers more accurately predict the impact of these events. (If it's a case of known-but-unusual things happening in part of the problemspace, that's an issue of defining the problem appropriately for the engineers, and can be corrected before the solution is implemented without a higher time-discount or margin of safety.)