What, exactly, is the persuasive counterargument for basic morality? Why isn't morality axiomatic?

Let's put it this way - the argument above would also apply to saying that a private citizen who catches a thief stealing their catalytic convertor can torture them slowly and painfully for weeks without actually killing them. You owe them no moral consideration, it's a deterrent, etc. Do you need someone to make a persuasive argument against the merits of that to realize that it's abhorrent?