Namely, well off white people. The people who know they are not the ones in danger of being killed. And probably not the cops, who’ll have to worry about getting dragged out of their cars and killed if they patrol minority neighborhoods after.
Not by gang members, but by enraged mobs of average citizens. Because another flaw in your psychopathic plan is that it ignores the fact that not everyone is going to agree with you that those people deserved to die, or were even guilty.
Two that come to mind is there’s no other way of solving the problem of many diseases, that it actually works ( unlike mass executions ), and that bigotry isn’t involved.
A society that does as you suggest would probably “solve” the problem of sickness among the uninsured by killing them. A murderous society is going to solve it’s problems in a murderous way. And no, I don’t think it’s unrealistic to think that a society that acts like Nazi Germany in one way will act like Nazi Germany in another.