And the plug plugs the tax hole!
A nice aspect (for the tax gatherer) of an universal 'smart' plug is that you potentially have the ability to tax "driving" electricity more, as you can do for fuel.
Indeed, you advocate an universal plug, for convenience. You then make sure that all the charging stations need a license, a meter, and a network connection (for service quality purposes, or "smart grid", whatever), that the car only starts charging when a licensed station is detected at the end of the cable (for safety reasons, of course!), and poof ! Electricity-for-the-car can be taxed as much as you'd like!