> If I moved to another country I would learn their language before and while doing so > so how is that a double standard?
It's a pity the immigrants to America 200 years ago didn't do that, or you'd all be speaking native American now.
English became the international business language because England took over so many countries. If Germany had been more successful in the first or second world wars then that would have become the dominate language.
English is a mixture of many different languages because England was taken over by so many different countries.
It's easy to say that English is the standard language of America so everyone should learn it, after you colonised the country and tried to eradicate the local language.