Very few people forget America is a country on a continent. Its the United States of AMERICA, so shortening it to AMERICA makes sense. You know how the United Soviet States of Russia was called Russia by some for short? If you say continents its more accurate to say the AMERICAS as a compo or specifically NORTH, CENTRAL or SOUTH America. One thing more of an issue is people saying things like Mexican migrants when referring to all people from south of the border. South Africa is in the Southern part of Africa but people still just say going to South Africa or SA for short.