[occamrazor]

Mistyped card numbers can be identified client-side (CC numbers have a checksum digit). If the number is valid, but the transaction is declined, then fail silently (and possibly send a failure email after manual review of the transaction)

[tomp]

It could also be declined because of mistyped expiry date or address or name. Or simply declined because the customer is over their credit limit. In all of these cases, timely feedback is useful for genuine customers.

[pc86]

Which is why it says in the article that these countermeasures almost always come at a cost to customers as well. It is a trade off.

In some instances it is worth it to make the experience marginally worse for customers because the savings by preventing a percentage of fraud are so large.

[duaneb]

Nonetheless, this doesn't contradict the "failing silently" for chargebacks. It's not fraud if they enter the data poorly or there's no credit left so the charge is never made.