It seems odd the more people of a certain blood type would sustain injuries requiring blood, or that people of a certain blood type would care more about blood donation.
For the same reason donating organs if one is mixed race is worth more (than organ donations by individuals of predominantly monoracial ancestry) because of complications in compatibility for the demographic.
Blood types vary by ethnicity, SES varies by ethnicity, injuries and donations vary by SES.
For the same reason donating organs if one is mixed race is worth more (than organ donations by individuals of predominantly monoracial ancestry) because of complications in compatibility for the demographic.