Asian Pacific American

After the class discussion about Asian Pacific Americans, I started thinking about common generalizations. Why do people group certain Asian backgrounds together? Why would someone who is Korean be referred to as Chinese? How have people become so ignorant? You wouldn't refer to someone who was Italian as Swedish. You probably wouldn't even refer to someone who was German as French. Why can ignorant Americans tell European Americans apart but don't seem to care to educate themselves with people who are different than "just white"? The Asian American umbrella shouldn't be any different than the European American umbrella. People from different places have their own identities and their own cultures. When did certain groups of people get bundled into the same group?