I mean, you sort of do! Every modern US car has a wheel to steer, a brake pedal on the left, a gas pedal on the right. Calculator UIs vary way more than that. In the US, you can drive a manual after training on automatic, but that's not true everywhere.

And in-car driving instruction happens with the teacher next to the student in a car they're familiar with. It's not like they're radioing to 30 students each in a separate car.

Also, the calculator is a tool to teach math. If someone gets distracted figuring out the calculator, they're behind. The student driver car is to teach driving.