First, why does the US still allow a death penalty?
Well, our judgement is that it provides a number of advantages. One advantage is the it prevents the convicted from committing further crimes. It's safer for the other prisoners, and it's safer for the guards. Another advantage is that it prevents others from committing particularly heinous crimes. I realise that there's evidence that such is not the case, but the evidence is not unequivocal; a reasonable person may still come to that conclusion. A third advantage is that it prevents people from declaring vendetta and taking vengeance. A fourth advantage is that it provides closure for the families and friends of the victim. Families don't have to keep track of parole hearings, and spend time and money testifying against parole.
We tend to argue how much a prisoner costs society, but rarely discuss the morality of executing people.
I disagree. We tend to discuss the morality of executing people ad nauseam. If there's anything left un-discussed, I think it's the effect on the executioners. Knowing that you've killed a human being is going to do something undesirable to your psyche. I worry what it does to them later in life.
Next, and relates to the first is that the Prison systems in the US have become a for profit business.
I don't have a problem with that, but then I think of profit as the price we pay for efficiency. I understand that there's something dissonant about imprisoning people efficiently, but it does have the advantage over imprisoning them inefficiently. Maybe it would be better to think of it as imprisoning people expensively versus not imprisoning them expensively.
The privatization of prisons has caused countless issues. Such as contracts requiring a specific capacity at all times in prisons and the exploitation of prisoners. Laws have been passed to help keep prisons at capacity...
I'm not aware of those events, but I'll take your word for it. That being said, and I'm trying not to be flippant here, I can't see how the one relates to the other. I mean--if one executes a prisoner then the prisoner is not maintaining the capacity of the prison, is he? How do prison businesses exploit a corpse? And aren't laws being passed to keep prisons at capacity a problem with the legislature rather than one with the business?
...nearly everyone in the US can commit several felonies every day without their knowledge.
Now that is a problem I worry about. We imprison more people per capita than any other country. We're not a particularly lawless people, are we? Why do we put so many in prison? Something is wrong. Now, it could be said that we aren't lawless because we imprison so many, but I think that's just plain wrong. I particularly decry the increasing lack of a mens rea in recently passed laws. What's the point of that!
We could discuss other issues, such as how rehabilitation in the US really does not exist and society lacks opportunity for people motivating people to illegal activities but can save that for later.
We should address why the US has the highest percentage of people in prison in the world,...
...and why we still have executions first.
Been there; done that; the T-shirt's stained with blood.