If you order a new iPhone, iPad or laptop from Apple, you can track the shipment from the factory in China to your front door via FedEx. I'm sure they're carrying tens of thousands of those batteries each day.
An aside: it's fascinating to watch the precision with which the package moves around the globe. I'd be challenged to get my body from home to a specific point in China in less than a day, but FedEx does it routinely with packages.
The batteries still have to packed according to IATA rules, and there are quantities limited for devices shipped in bulk.