Conversely, if you're trying to launch a space probe and the planets are no longer in the right positions for the required gravity assist, your spacecraft will not get where it needs to go. Or if you're a little $100M/yr toolmaker, and Ford asks you for a die for the 2026 F150 production line, to be delivered by March, and the contract states you owe a $20,000 per MINUTE penalty if you're late...you don't wait until February to say something surprising happened and it's not going to be ready. You don't sign on that dotted line unless you know for certain that you can do it.
Ford or NASA won't bat an eye when you tell them that a quote is going to cost $XX,XXX. They won't be surprised when they give you an ECO and you say that it's going to take 3 weeks and $8,000 to deliver a part that everyone knows you can probably make by hand in 30 minutes, they know that you're hedging against those deadlines, and pricing in the acceptance phase and inspection phase and contingency plans and everything else that makes their deadline-heavy industry function.
But if you tell someone at OP's modernization group that due to incomplete information you think that the 30-minute task to change the text of that button will take "no more than 3 weeks and $8,000" they'll laugh you out the door. Optimistic estimates get rewarded, pessimistic estimates get discouraged, accurate estimates are irrelevant, and in the end you're constantly behind schedule and no one's really surprised.