As Apple has never made hard drives, calling them a hard drive company makes zero sense.

The hard drive in the iPod was never the most interesting component, or the differentiator from the rest of the market. Tesla's battery is. The hard drive in the iPod is like the wheels on a Tesla. It's useless without them, but they're a completely replaceable commodity and has no bearing on the success of the product

The battery in the Model S is an array of commodity Panasonic cells.

What part of "tesla is going to build their own batteries" do you not understand?

Sounds like the headline of this article should have used the future tense.

Apple never manufactured their own iPod hard drives. That's where the similarity ends. Advancing the state of the art in batteries is essential for Tesla to remain competitive. For Apple, it was adding content and services.

Apple was (and still is, in some cases) a leader in miniaturization. They made a product viable that was never viable before.

Other drives were too big, expensive, and power-hungry. Apple made the iPod a common device because it was the first MP3 player with more storage than most people would need, it only cost a few hundred, and its battery lasted a long time.

Apple continued to compete by getting even better at miniaturization, like when they introduced the iPhone.

Eventually we're going to be arguing semantics, but my point still stands. Being the leader at manufacturing the boring internal components was necessary for both companies to provide the product that we perceive to be their core competency.

Edit: I forgot to address your point about manufacturing. They may not have manufactured the drives or had a unique technology, but they had advantages in manufacturing that no one else had. Tesla seems to be the same way, from what I can tell.