This is the reason why I don't like doing any client side validation of card data (beyond the basic check for empty fields).

I would much rather incur a 2-3sec browser roundtrip by posting raw payment details to my bank/gateway and allowing them to do the validation (they're presumably much better at it than I am).

Doing client side validation is too error prone, and considering that accepting card data is done so rarely, the (minimal) performance gain of JS validation isn't worth the risk of rejecting good data by accident.