This will never work. Components in cars are engineered to be organized as efficiently as possible. The overhead from having replaceable batteries will kill the amount of storage you can have.
There is no way you can have generic attendants swap out batteries in 5 minutes. Working with EVs is a dangerous job that you can't just pay an uneducated minimum wage worker to change. The batteries are extremely heavy and are placed in locations that you need a car lift to get to. Plus theres all sort of liability and safety issues from potentially messing up a battery swap or getting a bad battery and blowing up your car.