> I worry that the cost of exterminating people algorithmically could become so low that they could decide to start taking out small fries in batches.
My guess is that the cost of taking out a small fry today is already extremely low, and a desperate low-life could be hired for less than $1000 to kill a random person that doesn't have a security detail.
These costs would depend on the nature of the target, the nature of the country you live in and the requirements of the murder.
High profile, protected target? You probably couldn't find a random low-life to do it, much less successfully. And no matter what jurisdiction you want to commit the murder in, it will be more expensive than if your target was a random average joe, or jane.
Country is a place where the rule of law and legal enforcement are strongly applied and taken seriously? It will become harder and more expensive. Criminals are often stupid, but even stupid criminals in countries that take legal matters seriously are rarely freewheeling about contract murder that they actually mean to commit. The pool of willing potential killers would be smaller in such countries.
And finally, the nature of the murder: Need to kill someone in a way that looks like suicide or accident? That won't be something you hire a low-life to do on the cheap.
On the other hand, if you just need someone with modest to poor protection dead and you live in a country with weak legal mechanisms, then the situation becomes as favorable as you could want given your murderous needs. Assuming you have the right connections, a random gangbanger or would-be gangbanger on a motorbike can do the job for very cheap indeed. In the country I live in this is common and the people (often just teenagers) paid to do it will go for broke if offered as little as a couple grand or sometimes much less.
You're leaving out the cost of getting caught with risk factored in.
Also, if targeting small individuals, it's rarely one individual that's the issue, but a whole group. When Stalin or Hitler started systematically exterminating millions of people, it was essentially done algorithmically. The costs became very low for them to target whole groups of people.
I suspect that once you have the power of life or death over individuals, you automatically hold such power over large groups. Because you need a corrupt structure and once the structure is corrupt to that extent there is no clear line between 1 person and 1 million persons.
Also I suspect only one or a handful of individuals can have such power because otherwise such crimes can be used as a bait and trap by political opponents. Without absolute power, the risk of getting caught and prosecuted always exists.
My guess is that the cost of taking out a small fry today is already extremely low, and a desperate low-life could be hired for less than $1000 to kill a random person that doesn't have a security detail.