And then you'd have people who would try to rort the system by swapping a bad set of batteries with a good set from the station, and then sell it for a profit.
so either you're only allowed to swap batteries at these authorized stations (akin to today having a car that can only use petrol purchased from a particular brand of station), or it's trivially easy to swap it yourself (or with some easy to obtain equipment, like today's car oil change).
If it's the first case, then these cars are DRM'ed to hell and back. Not a good world for the consumer.
If it's the latter, then battery swapping will happen. It's https://en.wikipedia.org/wiki/Gresham%27s_law applied to batteries.