Originally Posted by
747FC
From the information you posted, it sounds like Visa is taking a hard line in the customer's favor, and making it clear to everyone that ignoring customer's DCC choices would be unwise for the merchant.
It might simply be a matter of chargebacks for the entire amount being much easier to deal with than dealing with what proportion of the charge to claw back, especially when exchange rates get involved. The consequences for non-compliant merchants becoming worse is a nice side effect.