Why would a country not celebrate this holiday

United Nations Day on October 24

The 24th October, each year is the International United Nations Day. This followed a declaration by the United Nations General Assembly in 1947 which designated 24th of October, the anniversary of the Charter of the United Nations, as United Nations Day, by proclaiming that the day would be instrumental in making people aware and it shall be devoted in making known to the people of the world the aims and achievements of the United Nations and to gain their support for its work.