Actually, this is not how the cars are considered. The "Other" designation comes from how they sort the Secretary of State license plate types. The IL Secretary of State has hundreds of types (some of them are special vanity types, etc.) and there are too many to put in pull down boxes on the web sites!However, EV's are consider "Vehicle: Other" (not a regular car IOW) for this system —not that they tell you that anywhere.
EV plates are not considered regular "Passenger Car" plates by the Secretary of State. They are their own thing. When there are enough EV plates so that they outweigh Motorcycles, Disability, Military plates, etc. then we'll get our own "Other - Electric Vehicle" plate type in the systems:
^ You may notice that EV's may be moving up in numbers within the "Other - None of the above" category as the Electric Vehicle plate is now the example image for the group.