I think many people think the US justice system has safeguards and is designed to protect the rights of innocent people.
Superficially that’s true, but it’s administered by politicians who can bend the rules whenever it suits them, and make judgements that defy common sense but which are not “unconstitutional” (so not subject to Federal challenge).
So in practice, wrongful convictions are commonplace, in serious cases perhaps 4% of accused people are innocent. Solving serious crimes is a tricky business, and there are going to be lots of mistakes.
Prosecutors with a weak case like the death penalty, because
(a) It allows them to appeal to juror emotions more strongly. There is a stronger presumption of guilt.
(b) It slows the entire process down, so by the time the truth is revealed (if it is ever revealed), the prosecutor has probably moved on and is now a judge or in private practice, or retired or dead.
A criminal justice system is a necessity, but society should recognise that convictions are not and cannot ever be certain, however much a jury is exhorted to respect the principle of reasonable doubt. People can be easily fooled, it is human nature.
So it is inevitable that there will be wrongful convictions. What is wrong is to suggest that wrongful convictions do not and will not happen, and to have extreme sentences that are unnecessary and serve no useful purpose for society.