>You can't stockpile gasoline for a long time without stabilizer.
If you have a vehicle that runs on gasoline, you don't have to store gasoline for a long time to have a stockpile.
The cost of a few empty canisters is by far smaller than the cost of solar batteries, and putting gas into a vehicle in case of an emergency within a span of seconds rather than hours is a huge asset.
Not to mention: not everyone has space for solar. City dwellers are particularly constrained (as in: people who live in apartment complexes).
I wouldn’t feel terribly comfortable storing gas cans in an apartment.
People who live in apartment complexes can have storage spaces that are appropriate for a gas can (basement, shed, etc).
Finding space for a solar battery installation is a bit harder.
Not to mention: your Cybertruck isn't going to power your 7th floor apartment. You can probably figure out why.