I tend to agree with those calling the Texas legislators "reactionary", because our system of vehicle taxes today in California is based partly on a fixed annual registration fee (that varies in part with the car's price/value and depreciates over time) and partly on fuel taxes (that vary directly with the fuel efficiency of the car). So today, people driving identical mileage can pay wildly different 'fees' to the state government, depending on the price of their car and the amount of fuel they purchase -- neither of which is particularly well correlated with the wear/tear on the state's highway system.
By taxing by car-price and fuel consumption, the government today is incentivizing the use of lower priced cars that get better mileage (Prius, Fit, Yaris, Smart). This is a perfectly valid social policy, if we also believe fossil fuel consumption has bad consequences (air pollution, dependence on unfriendly regimes, etc.). So leaving EV's the heck alone would be a logical extension of that social and tax policy, if we want more LEAF's and fewer Humvees. I won't pay fuel taxes to drive my LEAF, but I will pay an annual excise tax on a new $34,000 car (based on the pre-rebate, pre-tax credit price, mind you) and, as DarkStar already pointed out, city franchise fees and city taxes on my (higher) electricity bill.
I'm hopeful that the knee-jerk reactions of cash-starved legislators, who are fear-stricken at the idea of a handful of environmentally conscious constituents not paying "their fair share" to support highways, will prove to be just that -- knee-jerk reactions that don't get any traction. Worst case, all vehicles will wind up paying some 'per mile' charge, but I don't see anyone repealing fuel taxes, so EV's would keep that advantage.