How do you know it's for human trafficking? Are you deputized by the government to act as judge and jury?

If you think something might be for human trafficking, you report it to law enforcement and let them deal with it. They'll gather evidence, build a case, make arrests, and hand things off to a DA/prosecutor who will file charges. Or, at some point, someone will decide it's not human trafficking, or at least that there isn't enough evidence to prove it beyond a reasonable doubt, and drop the case.

All that is just due process, and a payment processor should not be given that responsibility. Both because I don't think they'd want it (it costs money and carries liability), and because we shouldn't trust them with it (private corporations shouldn't be allowed to apply the force of law).