Your argument would have been more convincing if the Asians were getting the same as British people. But as soon as the Asians do better, it means that the whole comparison is meaningless. It means that Asians and British scores differently. Maybe Asians normally should score 14 and British score 10, but they score 12 because the test is culturally biased.

(sure, we expect that a small difference in "normal situation" should be relatively small, but the samples are defined as biased, so you cannot really rely on them unless making unproven assumptions)