This is going to be immediately downvoted, but whenever I see software developers mention that estimating is uniquely challenging for software it immediately calls out a bunch of red flags. Estimates in software are challenging but no more or less challenging than other industries.

Typically the people that single out software as a unique snowflake in the world of delivery and estimation really just say out loud they have no experience in project management and no experience working outside of authoring code. The things that make estimations most challenging in software are the same factors that make estimations challenging everywhere else.