Here is an example of how one aspect of the UI could look like with NPC hauling. You right click a station in personal asset and you can “Send all”. It opens new window where you select destination, and shows the cost.
That is the concept in rough form. Numbers need to be balanced, i thinking shipping within a region is “cheap” but shipping inter region insurance will go up significantly. Maybe a 10% flat fee on top that probably shouldnt stack if the goods pass through several regions. Well thats it. Perhaps this can help demonstrate NPC hauler do not put player haulers out of sevice.