The problem is not how many people reported it, the good thing is that Sony identified that there was a problem with what they manufactured between Aug and Dec, and even if no one had reported it, obviously Sony felt there could be a danger. It's much better for them to recall a few million PSUs than have an international scandal with headlines going "SONY DOESN'T CARE IF OUR HOUSES EXPLODE!"... Know what i mean? The damage to their image would be huge, whereas by doing this it puts them into a position of "being good and preventive".
Also, i think there are laws, whereby if a fault is identified, and that fault is potentially hazardous, for health and safety reasons the company is liable to recalling their product and exchange it. I'd imagine the fine or sanction for failing to comply would be much much much higher than the cost of a few million PSUs. :smile:
