Nah. Corporations have mountains of money. They don’t need a little bit of free code. Sure, they’ll take it if it’s there, but it’s not necessarily that valuable to them, because they’re perfectly capable of building it themselves at low marginal cost.

What’s valuable to them is to drive the price of a particular product down to $0, if that will undermine a competitor in an area that the original company has no hope of winning, or if that product being free will cause people to buy more of their product. That is worth a huge amount of money and is something that they are otherwise unable to achieve.

"because they’re perfectly capable of building it themselves at low marginal cost"

Casual comment. Being capable doesn't mean it makes viable sense to build it on your own and how are you so sure about the "low marginal cost". It never is when you have to build something, anything.

Just to comment in the "little bit of free code" there are projects like python and numpy that would take ages to do properly and depending on the company would never ship (or function as reliably as it does right now)

Sometimes they're buying decades worth of debugging/testing

In my experience these "mountains of money" are not freely available to developers who need to get permission for spending it from their team-leader-with-a-budget. But YMMV I guess, lucky you!

That doesn't explain why they haven't written their own operating systems from scratch and why hardware vendors are so reluctant to publish their driver software source code.