As reported on a p2 post (pNPgK-6LO-p2), there is a collection of logos shown next to the "Credit or debit card" payment method radio button in checkout, but that collection does not include JCB. We do display the JCB logo on the credit card field itself when a JCB card is entered, but the request suggests that because the logo is not shown up front, users may not know that JCB cards are accepted.
FWIW, we also don't display the icons for Unionpay, Diner's Club and Discover. The main issue I think here is how to fit all these icons into the UI of the label.
As reported on a p2 post (pNPgK-6LO-p2), there is a collection of logos shown next to the "Credit or debit card" payment method radio button in checkout, but that collection does not include JCB. We do display the JCB logo on the credit card field itself when a JCB card is entered, but the request suggests that because the logo is not shown up front, users may not know that JCB cards are accepted.