Not true. I bet close to 100% know how to change the tires, replace the wipers, put on new brake pads (not that they are often needed on EVs), and add wiper fluid. These are the things most often needed on an EV…assuming not an accident repair. They also know how to change the oil. 
But even for the things that are specific to EVs, 3% isn’t that low considering the percentage of cars on the road that are EVs is low and most are near new.
Mike