Forecast of EV cars and EV charging stations

...Aren't charging stations supposed to charge multiple cars, the same way that petrol stations fuel multiple cars? IMO having one EV charging station for every EV car is a bit of overkill.

Well, most EV owners have their own chargers in their garages. Those chargers are indeed designed to charge just one car.

In addition to these, there would also be a few thousand public chargers. So I suspect the estimate was just rounded down to a million for the graphic.