But very same doctors and researchers deliberately infected soldiers, prostitutes, prisoners and mental patients as well as children from state schools, an orphanage, and country towns in Guatemala. We don't know they didn't do the same in the USA with people they thought of as less than human or that no one gave a shit about, because these experiments are not disclosed to the public. The Guatemala one was discovered purely by accident, by a Ph.d candidate working on a dissertation who got access to the doctor's notes and work who did the original Tuskegee study. As someone else pointed out, there's a long list of horrific unethical medical experiments done on US citizens and residents on Wikipedia, and those are just the ones that are unclassified.
Why is it so hard for you to believe that our government has done/does bad things to its people, even when you are presented with proof? I don't understand that kind of magical thinking.