These are actually excellent examples as to why the death penalty is terrible and we shouldn’t listen to the advocates for continuing this brutal practice.
#1 completely invalidates the practice by acknowledging that innocent people get killed by it. Amazing that you would make an “in the real world” argument as if that’s not where we live.
#2 has plenty of real-world data to suggest that life in prison is cheaper and more practical than the death penalty in ~100% of cases, further invalidating the practice as useful or economical.
#3 is just a devil’s advocate argument about a society that currently practices execution, and I have zero interest in a “if we must kill people” argument, because I absolutely have no tolerance for the state having the power to decide that its own citizens must die. Humoring that is complicity in murder afiac.
In all you didn’t answer my question because there is no valid purpose for execution than to satisfy bloodlust and to give the state ultimate authority over its people.