Completely normal, and even more pronounced on EVs given that the for mild drivers, the regen does nearly all of the braking. You can buy aftermarket rotors coated in other materials (e.g. cadmium) that are rust resistant.
Hi, No solution for rust after rain and washing the car. Some times you can hear more noise when driving 10 km speed. I gave my car to service for this problem. They lubricated some parts but still same.