Unfortunately most companies don't have a software culture or even understand it. Heck there are entire nations (like Japan) that are culturally at odds with software. It doesn't stop them from making software (you can't NOT make software in today's day and age), they just go about it in furtive, roundabout and ultimately very inefficient ways.

It's weird because modern software development borrows heavily from industrial process optimizations (some of which were invented and perfected in Japan, ironically) and there are clear, proven benefits to cooperation upstream in projects like Linux... and yet they still fight it every step of the way in the name of "IP".

It doesn't help either that there are countries (US, Japan, what do you know) that nurture the concept of software patents that have a chilling effect on sharing.