Yes. Contrary to popular belief, cells with 18650 and 21700 cylindrical form factors, despite being approximately the same size and shape as other 18650/21700 c

Yes. Contrary to popular belief, cells with 18650 and 21700 cylindrical form factors, despite being approximately the same size and shape as other 18650/21700 cells, are not particularly "general purpose" as you or I would think of AA or AAA batteries. Major customers would likely have their own variants and particular specifications on variable parameters associated with these cells. And battery pack makers cannot easily switch between cell types and manufacturers. Source: I used to work for a major 18650/21700 cell manufacturer. I have torn down many battery packs and cells and know what's inside. And, it's well publicized that only Panasonic cells were in Model 3s for ages. If picking and choosing cells were so easy, and cells are really commodities, then why would Tesla bind themselves to a single cell manufacturer? Answer: They wouldn't. Cells are not generally interchangeable, not by a long shot. That being said, I would not go so far to say the cells are "custom made". The packs, sure. But cells are close variants of the same technology and process, and many smaller and lower customers may just use the same cells from a single manufacturer. You are incorrect about batteries not needing high tech and high cost manufacturing plants. In fact, the requirements around cleanliness and process control are very high, for yield, cost and safety reasons. Capital equipment costs and knowledge base requirements are high. I'm not sure how they compare to the requirements around leading edge microchips, but I would imagine that they would want to use similar approaches. As far as shipping goes, cells are shipped around via air freight all the time. They are going to need to get shipped regardless at some point. And, to the contrary, given my experiences with ground freight in general, I would not want to send cells via ground services.