This is quite different from maintenance. You already pay upfront to have lower maintenance costs, so the gas/oil/maintenance savings argument do not apply here, I think.
You usually do not throw the car when it requires a major repair, but when the car is worth 2k with dead batteries to scrap and the replacement of the batteries costs 10k, while you can find a car that is OK to drive for 9k, it is considered uneconomical to repair. Because if you can just sell the car for 2k, pay 9k for another car, you are only losing 7k in the process. Replacing the battery costs 10k - the opportunity cost of replacing the battery is 3k.
This is why a car that requires an engine replacement (for an ICE car) is simply scrapped for parts instead of putting a new engine.
Now, this probably isn't for the average person, an independent dealer or a resourceful (and careful) car owner could easily replace batteries much much cheaper.
You usually do not throw the car when it requires a major repair, but when the car is worth 2k with dead batteries to scrap and the replacement of the batteries costs 10k, while you can find a car that is OK to drive for 9k, it is considered uneconomical to repair. Because if you can just sell the car for 2k, pay 9k for another car, you are only losing 7k in the process. Replacing the battery costs 10k - the opportunity cost of replacing the battery is 3k.
This is why a car that requires an engine replacement (for an ICE car) is simply scrapped for parts instead of putting a new engine.