Edit mode for a ListView

I wonder why the ListViewDataSource (the UITableViewSource for ListViewRenderer in iOS) is internal? This makes it impossible to customise the ListView for the iOS platform. I am trying to implement editing of a ListView on iOS but as I said this is impossible since that functionality is implemented in the table source. I fully understand why there is no edit mode available in the ListView or TableView but do not understand why it is impossible to customise such behaviour.