Do you mean carry an extra battery, or do an exchange? While you "could" do an exchange, similar to how propane tank exchanges work, do you really want to be trading your pampered battery in for some random battery with an unknown history?
Battery swap almost necessitates leasing the battery. You cannot reasonably own a $10,000 thing you swap multiple times a week. But leasing it works extremely well.
I assume that such a lease approach would have to carry insurance to cover battery damage, similar to buying coverage for car rentals. At least with car rentals, the insurance isn't very affordable, and leads to some people being irresponsible with the property.
The insurance for a car lease is totally affordable. And that's what it would be -- a long-term lease.
You would lease a battery for 3 or 5 years from a company, and then swap at that company's swap stations. They would bill you on something like total miles put on the vehicle or total miles delta put on at swap stations. You would have exactly one entity with which you would interact in case of battery issues: the company.
That's a much more scalable approach. Supercharging stations, etc, seem like an insufficient band-aid. Imagine a gas station with each pump occupied for 30 minutes a piece.
That makes the most sense. Imagine a Jiffy Lube style setup: you drive on to a station, robotic arms automatically remove your battery and install a new one, and you're on your way. Total time: under 2 minutes. Boom!
They had the dumb idea of using renewable energy for the charging stations and, here's the dumb part, BUILDING THEIR OWN CARS instead of licensing out the battery tech to all the car companies for cheap. It was pretty clear for all the glowing profiles that came out when the company was forming that the guy running it was charismatic but a flaker.
Changing it takes seconds, the entire operation more or less like going to the gas station to fuel a conventional car.