A project in management theory is considered to have a plan covering budget, scope and time / deadline [1].
Such approach makes sense in engineering disciplines [†] which benefit from centuries of experience -- say, bridgebuilding -- the current state of affairs in software engineering is that predictability of software development is sketchy at best. One cannot reliably estimate all three of budget, scope and time of a software project, especially when there are significant unknown unknowns [2] involved. There are well known examples of software projects ending up breaking two or even three of planned constraints of budget, scope and time.
So far it seems various iterative methodologies (usually cnnected to agile methodologies [3]) suit software development better. Those differ significantly from single-project approach -- development effort consists of successive small iterations, each greatly predictable on its own, and overall progress being tracked as velocity.
As unanticipadet problems are encountered, they are included into plan in natural way, with corresponding adjustments to budget, scope and time.
[1] https://en.wikipedia.org/wiki/Project
[†] sometimes a claim is made software engineering is not real engineering due to lacking in predictability
[2] https://en.wikipedia.org/wiki/Unknown_unknown
[3] https://en.wikipedia.org/wiki/Agile_software_development#Ite...
There are some projects that could be considered real engineering, usually safety critical applications running on at a nuclear power plant or on a spacecraft where everything is formally verified.
But the vast majority of software engineering isn't ran like a real engineering project
That's an interesing point. Could you please elaborate on the specifics of program management?