All EV vehicles and hybrids use a battery "pack" that pack is made of groups of individual smaller batteries.

A few things good to know is that each battery alone only puts out a little bit of power somewhere between 3 and 4 volts.. But that's not enough to move a whole car, so you string lots of batteries together and now it's 200, 300, even 400 volts.

Normally these are put together in groups, and you can have multiple groups in a single car battery.

But these batteries are also flammable if they're damaged. Much like a phone or laptop battery... But thoes don't normally move at 60mph, and are just one battery not hundreds together. So they need to be protected..

So you put the batteries inside a armored battery box under the car normally. Lots and lots of batteries in this box means the only way to fix them is to remove the whole box and in many cases, remove the whole group of batteries that have one single dead battery in it. And replace the whole set.. Since they're fused together it can be difficult or impossible to safely and properly replace a single battery cell.

There are lots of comments pointing out scooters in Asia with replaceable batteries... Understand the power demand on a scooter carrying two people is substantially lower than that of moving a modern American car. Modular and removable batteries really are not viable in a car without equiptment to do so, and the COST would be higher.. If a company did make a car with replaceable batteries let's be honest, they would 100% make the batteries a loaner you pay monthly or yearly to use, with the ability to exchange it at locations... But if you didn't pay, your loaner battery presently in the car would stop working. The other issue is that batteries are heavy, and often become structural to the car. To be removable means they can't be secured to the vehicle in the same way, and the car would need to be more reinforced to not require the pack for structural support. It causes a ton of engineering issues that just don't matter to a little scooter. And this is still side stepping that battery packs are liquid cooled, it's not just two little connectors from the battery to the car.

TL;DR often you CAN replace a cell group with a single field battery in it. But it still requires removing the whole battery case from the car usually, so it's expensive. Other ways of doing this would be less SAFE for the vehicle owner for a bunch of reasons. And safety and reliability are prioritized instead.