Visa is only interested in papering over potential liabilities to itself.
They can make the DCC providers swear the Test Act

"We, Bank of China Ltd, do solemnly and sincerely in the presence of God profess, testify, and declare, That I do believe, that in the Sacrament of the Visa transaction there is not any transubstantiation of the local currency into the cardholder currency at or after the consecration thereof by any person whatsoever...And I do solemnly in the presence of God profess, testify, and declare, that I do make this declaration, and every part thereof , in the plain and ordinary sense of the words read unto me, as they are commonly understood by Protestants, without any evasion, equivocation, or mental reservation whatsoever"


And BoC will scroll down to the end of the form, click "Agree", and carry on doing what it did before.