Having been on both sides of the conversations I can sympathize with both points of view. I’ve worked in places where code coverage was important enough to dedicate 4-5 person months to pull it through, but not every organization can afford that (this was on Scala 2 with Bazel, so not exactly relevant in this case). My hypothesis for why “nobody cares” is that “all those who care are still on Scala 2”.
We used to have such an entity for code coverage, which is the scoverage project. I haven’t followed closely, so I’m wondering why is code coverage now part of the Scala 3 compiler? I would assume that being part of the Scala compiler should guarantee some level of commitment, and perhaps a higher standard of quality, than an under-funded open-source project. If that’s not the case, it would have been clearer to leave it as a community project.