Why would the US electricity infrastructure care if the electrons come from coal heat or sun light? And if renewable power becomes cheap enough you can synthes

Why would the US electricity infrastructure care if the electrons come from coal heat or sun light? And if renewable power becomes cheap enough you can synthesis gasoline from air. Renewable power does not have to become incredibly cheap for this work. If the price of oil rises high enough that alone could make synthesizing fuel using solar power profitable.... in theory.