They mean to make money off this. Especially from people who have trouble with their credit lines. To pad profits, credit card issuers have shortened grace periods and pumped up late fees. Many issuers have whittled down the interest-free grace periods on credit cards from 25 days to 20. This means customers have less time to pay off balances and more time to be slapped with interest when they don't pay in full.
Mistakes are costly.
The shift in policies means consumers who want to be certain to avoid late fees have to pay credit card bills as soon as they arrive. If your due date falls at a time of the month when money is tight, call your issuer and ask them to change it. As the rules get tougher in general, they can change rapidly for individual consumers when a credit card company is sold. In the past couple of years, waves of consolidation have swept across the credit card industry. In 1998, more than 20 million Americans held credit cards that were taken over by new issuers.