What am I missing here? Shouldn't the phone end of a cord only be a few volts? Is the article talking about people dropping power strips into the bath?
I thought the same thing, although I have heard it's not the voltage but the current that kills. Also in most modern households(at least in North America), bathroom electrical outlets are required to have a gfi or ground fault interrupt circuit breaker, to prevent accidents like this from killing.
Cheap, off-brand USB chargers often have poor or no circuit isolation. Some have even been tested to expose one leg of full AC current to the USB ground. Not a problem until you're between that and a ground.