When experiments were done on the blood of black men who thought they were being given medication to ward off syphilis when in fact they were being given the disease itself without any treatment so the gubment could see how the disease progresses without any medical mitigation. Some of the men already had syphilis. Some did not. They toldit was to rid them of "bad blood".
So black people do not trust yielding their bodies to "the government" for whatever they are told it is for. They lived through and died for having done that many decades ago.
If you was them or they was you would you?