Okay I want you to try to understand what I'm saying.

When Romans crucified people, they understood this act of torture as punishment for a crime.

They believed that torture as punishment for a crime was moral. The motivation for the act of tortured was incorporated into the moral valence of the act as a whole. This judgement of morality was not extended to all torture always.

What changes between one society and the next is the construction of frameworks of moral justification, and which of these frameworks are considered valid and which aren't.

Why does every culture that torture people in morally sanctioned ways devise justification frameworks?

There is a universality to the idea that torture requires a justification. That it is not an act that can be done wantonly or without reason and still be a moral one. And it's precisely this fact that approaches a sort of moral universal.

"Thou shalt not torture others without reason" is as close to a universal commandment across societies as there exists. While cultures will disagree on what constitutes a valid reason, they will all agree you need one.