So many foods eaten in North America are covered with cheese from pizza, lasagna, and tacos to sandwiches and nachos. When one grows up with such food and its flavor, eating high volumes of cheese is habitual. When it becomes so ingrained in the diet after many years of consumption, it takes great effort to avoid cheese, but many people acknowledge the health benefits of doing so.
It is also interesting to note that Parmesan cheese in not a vegetarian food since calf rennet is used in its production. Many times this cheese comes as an ingredient in a restaurant meal without forewarning, so it's important to ask the server when eating out if Parmesan is used as discussed in this article from The Guardian.
Also this article mentions that the EU plans to make labeling food as vegan or vegetarian a legal practice by 2015. This should help consumers make safer food choices.