I have sent several bugfixes to software I used as a "daily driver". I did the same when I was working at Amazon. While managers didn't usually understand the benefits of saving a minute or two from the test suite runner, at the scale I think it had tremendous impact. Especially when it comes to the cycle time during development. (Also relevant during the agentic workflows)

Since the code became a commodity, it is beneficial for companies to "open source" it. As the cost of doing so is negligible compared to the "responsibility transfer" by acquiring a license.