Americans usually say to British:" you write what you don't pronounce", and due to the US history, you can see that first generations came from Ireland , Holland and other Anglo-Saxon countries ,and as a result their descendants had tendencies to use simple words as grammatical structures and this what will you notice in the American English. What I noticed too is, that many of those who’re learning American accent reduce it in wanna, gonna, gotta and other slang words. It’s beyond that!
Thanks for the topic sis,