In most of the world, gasoline is mostly tax already. The US is an exception.
E.g. in the Netherlands the "raw" price of gasoline (a few months back) was 0.61 euro/liter to that, add 0.6 gasoline tax and then add VAT, to come to the price at the pump (pump costs + profits come are included in the 0.61 raw price) of 1.46 euro/liter.
So about 58% of the cost of fuel is tax.
This is ignoring various other taxes that have to be paid, such as foreign taxes on the gasoline, profit tax, company tax, transport tax, road tax, approval tax, vat on the vehicle you're powering, ... All those taxes are either included in the raw gasoline price or are paid separately by the customers. So let's minimize that and say that 70% of the cost of gasoline really funds government (though not necessarily the local one), and should be considered tax (I do believe it'd be closer to 80% if you went really deep). Now of course, a number of those taxes are implemented on electric vehicles as well.
There's no way the government is going to let that tax income lower when it starts eating into their budget, so there will be some sort of tax, probably doubling the price of electric vehicles in the next 10 years or so.
And this is tax. It doesn't matter that you're not doing anything negative to the environment. Already the government is taxing companies generating their own electricity (the Netherlands) in various ways, and they're talking about taxing people who cut their grid connection.