The software industry has been in existence for around 60 years. That was when the foundational ideas of Alan Turing and the genius of John von Neumann were turned into practical usage. Project management has been around for millennia, the Pyramids didn't build themselves. But in it's modern recognition as a separate profession it is also about the same age. Similarly modern business management became a teachable subject around the same time.
Yet the three practices do not co-exist in harmony. You would think that after all this time that they would have worked out how to relate to one another, understand each other's needs, and develop common series of practices: Construction has, movie production has, automobile manufacture has. Software? Not really.
Software has developed many astounding applications and enabled devices that where in the realm of SciFi a decade or so ago. Yet the number of projects, large and small, that fail is high. The UK has been trying to create an integrated system for it's healthcare system for decades. Best minds employed, big budgets, etc and it's been one failure after another.
You could argue that it is only the big complex systems that fail, but ask any internal IT department about the success rate of their projects and you'll get a deluge of horror stories. A lot of companies have trouble consistently delivering $50K projects on time and on budget.
Even if the project and software teams have a methodology they have a hard time of explaining their process to their business management. Software projects may be moving to a more flexible iterative process and yet their executive management is still wedded to point in time solutions. "How are you tracking to your milestones?", is a common question. Explanations of the new approach elicit nods of understanding, followed by a repeat of the same question.
Executives are not educated to handle uncertainty. They are trained to expect firm dates and to track to them. Their "profession" lacks the intellectual honesty to admit that they cannot predict outcomes. They expect, no demand, definite dates and expect everyone to stand by their initial estimates, no matter how circumstances change. They are in a state of intellectual denial, in an intellectual void.