That isn't good enough!!! In order to get a card, you have to read and sign the agreement that says "For Official Business Only". (Even if the forms weren't read and signed correctly, you implicitly agree by using the card.)
The way I see it, the sailors who used the card for fraudulent purchases are guilty of Dereliction of Duty under the UCMJ and should face those charges. For that matter, the financial folks on the bases and ships who didn't catch the abuses before the audit should also face Dereliction of Duty charges.
As I understand, you don't have a choice, if you travel, you have to use the Government Credit Card.
That's asking for abuse. As noted the worst abusers were enlisted, they may not even have their own credit cards. I've known enlisted (and some officers) on payday to go out and blow it all, then wait for the next payday to do it again. With the credit card, every day is payday
As the old saying goes, You Reap What you Sow Looks like the Navy (and other services) will need to conduct credit card training. Something else to get in the way real training.