The FTC's complaint found that Apple "does not inform account holders that entering their password will open a 15-minute window in which children can incur unlimited charges with no further action from the account holder." As a result, many parents racked up significant iTunes bills when their children took advantage of the loophole to purchase virtual items, currency, and other in-game bonuses without permission.
The FTC notes that Apple has received "tens of thousands of complaints" from affected parents in the years following the App Store's launch. One child reportedly spent $2,600 of her mother's money in Tap Pet Hotel, and several parents were hit with hundreds of dollars in fees after their children played games like Dragon Story and Tiny Zoo Friends.
The UK's Office of Fair Trading levied similar complaints last year when it launched an investigation targeting pressured purchases in childrens' apps. Apple previously issued over $100 million in iTunes gift certificates to reimburse unwanted fees from Capcom's microtransaction-supported Smurf Village.