CBA has entered BNPL!, page-8

Especially when a credit card that you pay off in time is far cheaper in fees than this "interest free" offering.

No it isn't. The fees are between 8.8% and 14.4%. This is lower than typical interest rates.

Afterpay customers use it because it's free and can discipline themselves to pay on time.

APT is not free. The cost is hidden in merchant fees which are passed on to customers.

If they can't discipline themselves they get hit with massive late fees and penalties on every single outstanding transaction. That can amount to hundreds of dollars a month in fees.