Why would the law being different mean they wouldn't use 3DS though? Surely it'd cut out a good amount of fraud along with the realtime monitoring? I understand that US consumers don't have a stake in this, but can't all the banks just agree to enforce 3DS? I can't imagine Americans are going to stop using their cards because of a small amount of friction added

> can't all the banks just agree to enforce 3DS

They could, but it's one of those things that really only work if everybody joins. Because 3DS is rarely used right now, a portion of merchants don't even support it, so if you start enforcing is as a single bank, your customers will start complaining their card doesn't work. The banking industry in the US is also more decentralized than in the EU, so getting everybody to join in simultaneously is hard.

The window of opportunity for 3DS has also more or less passed, the industry is moving on to the next generation of tech (wallets/tokenization), that should be both easier to use and more secure.

Because adding friction will deter many impulse purchases. Americans use credit cards constantly. The equilibrium would be perturbed in a way very much not advantageous for the credit card issuers if consumers became more cautious about using credit cards.

It’s the same reason credit card issuers are willing to pay Apple a few basis points to participate in Apple Pay: reducing friction has a non-linear impact on propensity to pay.