It may matter on academic considerations, people can discuss it, but it doesn't matter on global regulation layer whereby fairness is determined via collective

It may matter on academic considerations, people can discuss it, but it doesn't matter on global regulation layer whereby fairness is determined via collective consensus and for forseeable future, per capita is what everyone can live with. Your last point is signficiant because the rhetoric of total emissions isn't going to fly especially if the numbers make west look worse. In context of OPs post, trying to unilaterally frame climate debate around total emission in US and somehow turn that into geopolitcal leverage is not realistic especially if closer interogation of metric is against most major players interests. I don't think it's splitting hairs rather than acknowleding geopolitical constraints over what's workable and what's not, even if what's workable is suboptimal.