But compared to what? Most software continues to be bespoke/new work. If a different team/process was used would we have been as successful/spent as much money.

This touches on the classic question of "is coding engineering or art"? If it were engineering, it would become quantifiable once we have enough empirical data from previous projects to base our theories on. If it were art, that would be impossible since every project is as individual as the last one. It's probably inbetween.

Engineering is just applied science. And other engineering fields experience the same types of failure that software engineering experiences -- cost overruns, undefined requirements, unseen technical hurdles, etc.

that's the same by saying your kids are successful just because they were born.

"just because they were born"

Thats an example of a successful pregnancy project.