Traditionally, dark chocolate contains more cocoa and less sugar. However, the chocolate bean is very expensive and some chocolate manufacturers have been looking for a way to label their produce "dark chocolate" without having to actually use more cocoa. It's like almost everything else in the food manufacturing business. It all comes down to money.
Why is this important to the consumer? There are several reasons:
First, the mass media has been touting the antioxidant benefits of chocolate and since dark chocolate traditionally has more chocolate, most consumers think that dark chocolate is healthier in terms of antioxidants.
Second, some consumers are fooled into paying more for "special" dark chocolate. Manufactures are very clever with their packaging to make dark chocolate look richer and more decadent. In doing so, they often think they can get consumers to pay more.
Here's one trick that chocolate manufacturers pull to make their chocolate look darker but not contain any more chocolate. They use alkali chocolate which is a chocolate that has undergone a process called the dutch process which makes cocoa powder less bitter for baking purposes. However, what it also does is make cocoa powder darker.
Another thing to keep in mind is that the USDA does not have any rules regarding the labeling of "dark chocolate." So, food manufacturers have been free to label almost anything as "dark chocolate" whether it is dark chocolate in the traditional sense of not.
Buyer beware! If you are looking for true dark chocolate, you will want to avoid chocolate that has "alkali chocolate" or "dutch chocolate" listed on the ingredient label.

