Energy is finite and everything has a cost. Lithium batteries don't last forever, and using electric car battery to power a home will shorten the amount of driving lifetime.
Fuel for a vehicle is expensive and dirty, so only ok for emergencies.
A bunch of solar panels with battery storage is currently the most efficient and cost-effective particularly in an area with a decent amount of sunshine.
Apples and Oranges. A 5Kwh battery with inverter, is less than $1,000 U.S. That truck cost $50,000 or more. If you can afford that truck, you can also afford a backup system for your home that also allows you to use the truck for other things during an emergency.