"Battery passports" to track the raw materials used in making electric car batteries are proposed as a way of enforcing environmental regulations on mining world-wide. Critics question whether the system gives the mining companies too much influence in the system, which they could use to cheat.

I support the system for that purpose — but if businesses start offering to change out your car's battery as a quick recharge, it is crucial that those businesses not be able to examine the number of the battery that they get from you. That would become, in effect, another system for tracking where you drive.

The same reasoning applies to ordinary charging systems for cars. They must accept anonymous payment and they must be forbidden to get any identifying data digitally from the car.