We could solve that problem for cars if we standardize the batteries. Different cars with a different kW consumption could use a different number of the same standard battery. Instead of recharging we could swap batteries at the power station, an operation that might be automated and take no more time than filling up the tank with gas. But that means we have to trust the power station more than we do with gas stations now (at least until it becomes commonplace) so that might require a higher control, maybe directly by the car manufacturers.
On a related thought, liquid fuel is so convenient to stock indefinitely and distribute even in rural areas... I wonder if electricity will ever completely replace it.
Another problem is which wire you need to move all that energy into the capacitor in that little time. This applies both to the wire from the wall to the device and the one from the grid to the house (where I live residential contracts are usually limited to 3 kW). I didn't do the math but assuming it's not a problem for a cellphone it might be a problem for a charging a car fast. In a reverse-car analogy it's like having a 2 Mbit DSL to the Internet. Downloading a movie is going to take a long time a Gigabit home network won't help.
It's not an International System unit but it is (somewhat) metric, because it has been agreed to be 1852 m (actually, by this line of reasoning the inch is metric too as it has been defined to be 2.54 cm).
It is based on a natural measurement, the length of a meridian of the Earth. That is 360 degrees and a nautical mile is a 1/60th of degree. Not all miles have the same length according to this definition and not all countries used the same definition so, to make a long story short, countries settled for those 1852 meters almost one century ago. By the way, the knot is the corresponding unit of speed (nautical miles per hour).