I think you significantly underestimate the number of CI minutes people are using in practice.
(Which, yes, has implications for energy use/climate change too for sure).
It doesn't look like i currently have access to the usage data on any of the lots-of-runners-lots-of-PRs projects I currently work on (which are still probably way less than some large companies).
> some large companies
Any "large companies" don't give a shit about things at this cost level. They spend more on the time it takes you to open the door. The number of CI minutes could be astronomical and it still wouldn't rate above the threshold of caring. The time people in this thread have spent wringing their hands is way more expensive.