Actually, less than economy of scale its cost of the batteries. The batteries use rare earth elements that currently have limited mining output. Domestic production is almost nil, though improving with the re-opening of the Mountain Pass CA mine owned by Molycorp.

Otherwise, most of the supply come either from politically unstable areas or China.

Once battery tech improves and prices come down due to prospecting new mines over the next decade, electric cars should become more viable regardless of govt trying to push it.

Ofc there are other issues, but mostly it still revolves around production costs for the batteries.

For who could be free when every other man's humour might domineer over him? - John Locke (2nd Treatise, sect 57)