In the US why dont they call football soccer and soccer football?

Answer 1

Probably because in the USA the single word 'football' is more commonly connected with 'American Football' rather than with "association football" - also known as 'soccer'.

In those countries where another brand of football is much more popular than soccer, those more popular football games are what those regions call "football". There are many of them.

'Soccer' was originally a slang name for the game played in accordance with Rules set by The Football Association in England, where the game is sometimes still formally called 'Association Football', perhaps as a way of distinguishing it from other forms of football including American, Australian Rules, Gaelic and Rugby, to name a few.