Same as you can refuel diesel in your petrol car.

In the U.S., at least, diesel fuel dispenser nozzles don’t fit in a typical gasoline car. The engineers have intentionally designed standards to reduce human error.

That’s what should happen with any home electrical appliances, to reduce dangerous practices. It can’t be eliminated entirely, but things should be designed assuming that people don’t follow directions and don’t read the manual, have safety features that physically or electronically prevent power from going to the wrong place or in the wrong quantities.