An issue with a regional fuel tax is the residents who live on the very fringes of an area; think of someone on the Kapiti Coast or the Hibiscus Coast or Pukekohe. If you live in Dairy Flat, you're going to drive to Orewa to fill up, not Albany, so you avoid paying the tax altogether.
By comparison for Wellington, people between Pukerua Bay and Paekakariki would probably drive to Paekakariki to avoid paying extra for fuel (instead of getting it locally or in Porirua), and not contribute anything to the regional fuel tax at all.
A nationwide fuel tax is the best way, IMO...I'm just disappointed to hear that the train station upgrades and integrated ticketing probably won't happen now
