Make no mistake, if the US wanted to end money laundering in its backyard, it could do so. These jurisdictions exist because they provide value, especially to people with the influence to stop them, who see no reason to interfere in a system that benefits them without personally hurting any individual. Any negative externalities are sufficiently diffuse so the public can't pin the blame for the continued existence of the system on any individual beneficiary of it. So why would anyone stop it?