I had the same question — I understand that the Actions control plane has costs on self-hosted runners that GitHub would like to recoup, but those costs are fixed per-job. Charging by the minute for the user’s own resources gives the impression that GitHub is actually trying to disincentivize third-party runners.

or some other metric like how many logs your job produces and they have to process

the only rational outside rationale is this has the best financial projections, equitability with the customer be damned

gotta make up for those slumping ai sales somehow, amiright?

Because the competitor services that provide much cheaper hosted runners also charge per minute.

This isn't aimed at people actually self-hosting; it's aimed at alternative hosted runners providers. See this list

https://github.com/neysofu/awesome-github-actions-runners