Why are Roal Daul movies American?

Matilda, fantastic mr fox, when the books have English characters and were written by an English narrator?Why are Roal Daul movies American?Not sure I think it is because most movie production companies are American and so are the actors in those movies. Since they're children actors in some of the adaptions the accents wouldn't sound accurate. With Fantastic Mr. Fox I think it is because Cloony is a popular actor and is known as a American.Why are Roal Daul movies American?I have no idea but I bet you were watching Matilda just now!