With phones and regular usage you are likely doing full charge/discharge cycles every day or two, which is hard on the battery. That's not really the case with electric cars. When you have 200-300 miles of range, and you only regularly drive, say, 20 or 30 miles per day, it's pretty easy to keep the battery around 70%-80%, which should significantly extend the life span.

Obviously the batteries still degrade, but they should be usable long past 3 years assuming regular driving habits.