The electric cars 100 years ago were functional as a form of transport.
Both nuclear fusion producing energy and an electric car capable of driving some distance were demonstrated long ago. At that moment, neither was economically viable compared to alternatives (both based on combustion). Both remained in that non-viable state for decades. Electric cars seem to have crossed the border of viability in certain niches; fusion power still has not.
Also with highways, gasoline cars could make do with less infrastructure required to actually use them.