There is nothing stopping you from purchasing the movie and editting it yourself before showing it to your family. You can't do it and sell it to someone else.
I don't have the equipment to do that. Several of tese companies started out when the customer would send in the original and they would use their equipment to make the requested cuts and would then send back the original with the edits. All they have done is streamline the process and make the original purchase themselves. Can they revert to the old business model and edit a copy I send them now?