Energy efficiency. Electric to gasoline to wheels is probably something like 75% * 50% * 30% == 11% efficient (roughly, very roughly). Electric to battery to wheels is approximately 77% efficient.

We'd need 5 times the power generation capacity, or more, just to support that use case.

The fact that we burn over a million tons of gasoline a day (in the US alone) is a secondary issue, but even by itself that's a hell of an engineering problem to solve. Aviation use is less, but still a lot.