People today now use the internet to find out every topic imagineable, things which under normal circumstances they would have trouble finding info about any other way. People even search for a particular car licence number, to discover who owns a particular vehicle or car. Why would people be doing this? well, its actually quite common, maybe someone wants to investigate the driver of a vehicle, maybe someone has noticed a car in their local area and wish to investigate as they may have been acting in a suspicious manner. There are places online which offer plate lookups and which can also provide full background checks so you could in theory find if someone has a criminal record or if they are who they say they are. See reverse phone lookup