Look, you can design this new luxury truck that runs on sunlight and is better than a diesel truck in every aspect.

But that shit obviously costs a bomb and nobody is going to buy that.

Seems like a good idea, but for every organisation, the bigger picture is value for money and revenue.

By contrast, a smartphone is something everybody needs, there is a large market for high end phones like iPhones and Galaxies. Everybody needs a car, at least in America, so that could also work.
But the only people who would buy such a truck are people who love trucks. People in general do not need trucks, businesses don't want to spend a fortune on logistics. So he's trying to create a premium or luxury market of trucks when there isn't really a demand for it. A truck driver would rather show status by flaunting the latest smartphone, watch, or driving a high end car.

But then maybe the point of it is just to say "hey look what we can do", a logical continuation from the Tesla car, is the Tesla truck, then the Tesla motorbike, then the Tesla bus, then the Tesla train, etc. So it's like throwing an idea out there, but also throwing a lot of money out there. I would have skipped the truck and invested in producing a Tesla saloon variant, a hatchback variant, an estate variant, a 4x4 variant etc instead, which evidently does have large consumer demands.