Do you live in a country where you think the laws are reasonably in line with what you think is just? Do the decisions of your courts usually meet your expectations in this respect?
There are many things wrong with the laws in the US. I'm not even sure where I'd start
But the other bigger problem is enforcement. Some people do a murder and get a nationwide search. Others the victims family get a "lol can't help you".
Recommend reading "the new Jim Crow" for one look at one part of this.
I became anti-death penalty because the real world data of how it has been applied clearly shows the state does not apply it evenly to all. It disproportional is applied to people of color. Moreover, the state has shown it doesn't convict evenly, so not only can people be wrongfully convicted at a higher rate for some, but they can even be put to death by the state. So innocent people are being wrongfully convicted and even put to death. Until we, as a society, can apply laws and punishments evenly, we cannot have laws and punishments only for some. So the death penalty should be off the table.
Fiscally, the death penalty is also more expensive to enforce than life in prison. So ethically or fiscally, the death penalty should be abolished.