It's much worse than that. Every manufacturer uses a different style, size, layout, battery pack. Most, like Tesla, also have a coolant system attached to the pack. Those, as of right now, are not something that can be quickly and easily detached and reattached. There's also the issue of ensuring replacement of any coolant that leaked out during the swap. Even within a brand not all battery packs are equal.
Let's say you come in for a swap in a Tesla. The battery pack they give you isn't the same model that was taken out. Let's say the swapped in one has more range. Tesla, monitoring your car sees this and slaps a range restriction on you because they can.
Tesla Sued For Allegedly Crippling Range And Battery Life With Software Updates
https://www.carscoops.com/2023/05/o...eaking-their-batteries-with-software-updates/
Or, your battery has issues, serious issues. The car runs but has tens of miles range available because of these problems. You come in and get it swapped out. The new battery you got has the full available range on it and the swapping company is stuck with your useless un-rechargeable battery. You make out like a bandit.