As I pointed out in another thread about these vehicals, the USPS still operates mule trains, hovercraft and helicopters for some deliveries. That's the most extreme examples, and I imagine there are many journeys that are somewhere between in terms of range and difficulty. People have a very narrow view of the world and forget that not everywhere is urban or suburban, or even just farming country levels of density. The USPS has to service them all.
Grumman LLVs only have a 120 mile range. This is already double. And sure, maybe you’ll want an RV style outlet (also pretty cheap) in case of 5% of vehicles where 120V wouldn’t be enough.
