Re: I've never understood...
Most likely a tax on electricity supplied via an electric car charging point.
You could avoid that by charging from a 13A domestic plug, but it would take so long to charge a car with a reasonable range, that it probably wouldn't be worth the effort.
1 litre of petrol is about 10kWh, so it would take about 3h 10m to get the equivalent of 1 litre of petrol through a 13A plug. A typical petrol pump pushes through 50 litres per minute.