How and why it works that way? Here is a rundown of Xbox games through the cobweb called marketing: the first company mass produced game and its packaging, distributing them to various stores across the country, the game gets sold, then the money is divided between the trade itvrtka that produces the game.
How often do people play backup xbox games? In the United States is not really a major concern because many people buy a genuine copy, because you already comes with the package deals and promoting accessories such as maps, brochures, posters and a DVD with special features included. In other countries, although, like the Philippines, marketing copy disks all over the place. These people often can not afford the price of the original scales so they buy and play backup xbox games instead of the original disk.
Is it wrong to play? It all depends on who asks and who answers. Copy it to yourself, keep it at home and use it when the original copy is broken. Do not sell this disc by anyone. It will keep you ahead of the law.