Just now saw a innocent girl been over-charged again by EZ-Link system that implemented on public transport in Singapore. She encountered error when alighting, so she went to the driver, who asked to tap on the "Entry" sensor again. The driver then asked the girl to tap on the "Exit" sensor at the alighting door, but the girl just didn't understand. So the girl had either over-charged for the rest of the trip that she didn't take (the EZ-Link system works in such a way that maximum fare will be deducted when boarding the bus, and the change will be refunded when alighting the bus, provided you remember to tap your EZ-Link card to the sensor), or even worse, be double over-charged for the trip.
I think EZ-Link is the only system in the world that can legitimately over-charge consumers, without being penalized. Thanks to the blame on consumers, and the fact that it's only launched in obedient Singapore society