That means that if you think of your gas tank as a battery that stores energy, and if you think of the pump of a generator that is the source of that energy, the gas pump is the equivalent of a Diesel engine capable of powering a freight locomotive.
That's equivalent mechanical energy. I'm not counting the thermal waste energy, because that's basically the same whether your car engine is generating the shaft power, or some electric power plant somewhere is generating the shaft power.
So now, think of this: if it were possible to load a full charge into a car battery as fast as the tank can be filled from a normal gas pump, and if the battery could hold as much equivalent mechanical energy as does the gas tank in your car, you would need the generating capacity of a 4000 hp Diesel for every pump in every gas station. That power generation capacity would have to be there 24-7 for every gas station in the country.
Not necessarily true. You can charge a car overnight, when electrical demand is low, and you take more time charging. About 20-30 years ago I read in IEEE Spectrum magazine that the energy transferred by a gas pump is 10 MW. In order to recharge a car at the same rate as a gas pump would require a 10 MW connection (even if we ignore other problems.) An extended range Tesla can go about 300 miles on a charge, so can a Corolla on a tank of gas, maybe a little further. Might take 5 minutes to fill the Corolla, 8 hours to charge the Tesla. Say it takes 5 hours to drive 300 miles. The availability limitation imposed on the Corolla by refueling is on the order or 5 HR / (5 + 5/60) HR = 98.4%. Similar number for the Tesla = 5/(5+8) = 38.5%.
As long as you can limit your driving to 300 miles in a 13 hour period, the Tesla should serve your purposes. If you want to drive more, not so much.
This ignores the impact of A/C and heater.