Freeborn,
This is why I think that the word "drove out" is far more forcefull in meaning.
Like driving cattle out of a field. They force them in the direction they want to go.
I just believe that God had to drive Adam out, because he refused to go when God said leave the Garden of Eden. Would you want to leave a garden that God gave you to protect for maybe millions of years? No. Adam had become arrogant in HIS position. Please remember that he blamed God himself for making the women, that gave him the fruit of the tree of the knowledge of good and evil. God had to force him out with force out of that Garden! I bet Adam was fighting God all the way out.
Cast out, like in regards to Satan from heaven. God just grabbed him up and threw him out with his 1/3 of his followers. God gave no second thought of it. Satan did not either, because he wanted out. Adam did not want out of the garden. Satan wanted out of heaven.
That is my thought. Tweety