cause they have there own government
British
yes you can use sprint in other countries
no
Foreign policies.
"I'm pretty sure just the United States... hence the US Constitution" - not true. Many Latin American countries when they became independent from Spain copied and translated into Spanish the US constitution word for word. However, they often did not follow the constitution because they did not have the same history and value system.
Yes, they use them to get into other countries
Only Chinese use yuan. No other country does.
Only two countries use ZIP Codes: the United States and the Philippines. Many other countries have postal codes that use other names (postcodes, PIN Codes, etc.). Some countries do not use postal codes at all.
Oil.
weapon
EVERY country in the world except the US does not use the 12th. amendment to the US constitution. This is because they have their own laws.
can you use mobile in usa from other countries