I've also seen it argued that real world estimates for things like construction projects are so good because 99% of it is do-overs from similar projects in the past; everyone knows what it takes to pour a column or frame a floor or hang a beam.

Whereas with software most of what was done previously is now an import statement so up to 80-100% of the project is the novel stuff. Skilled leaders/teams know to direct upfront effort toward exploring the least understood parts of the plan to help reduce down-stream risk but to really benefit from that instinct the project plan has to regularly incorporating its findings.

Real world estimates for construction projects are often way off. Especially for remodeling or renovation of older buildings, where the most serious problems can remain hidden until you get into the demolition phase.