While it is true cars are parked the vast majority of any typical day, the lack of charging infrastructure is the actual hurdle.
Many people with homes do not have garages or other locations with accessible outlets. Parking on the street is extremely common in dense neighborhoods.
Many people live in apartment complexes with either open parking lots or with sheltered spaces that don't have electricity.
Both can be solved with more infrastructure for charging and more EVs that can plug into regular outlets for slow charging.