Huh? Sensible racial grouping is trivial. The overwhelming majority of people on earth fall neatly into racial cateogies of white (European), black (African), Native American (American Indian), or Pacific Islander. Sure, the edges are fuzzy, (and good luck with the whole race/ethnicity thing vis-a-vis hispanics) but to pretend that makes it difficult to measuring population-level averages is just silly.
It's much easier to offer up a flippant rhetorical parry than to actually make an argument. Cognitive dissonance and all that.
Here's a question: How is it that we're able to measure the degree to which various racial minorities are underrepresented in congress, in colleges, in industry and in Emmy Award nominations? How is it that we're able to measure racial disparities in income, in COVID exposure, in medical outcomes and in every other conceivable context, if race is such a tricky concept to nail down?