Sounds like Communism to me. That system killed 100 gorillion people.

Or put the batteries in your home, charge it during the day on solar or whenever electricity is cheap, and use it whenever.

It can even be less dense batteries that you don't need to put in cars.

Yup that's the free market , if someone can see a business case in operating a big battery by taking money to use the excess power and then again taking money to sell it back when needed everyone will be happy. Of course doing that will reduce the price difference