The necessity of modularity is a numbers thing.
When I grew up there was the
MSX standard for microcomputers using the same basic design and BASIC, which was adopted by several computer manufacturers.
To no avail, as the Commodore 64 blew them away in sales. At one time the C64 sold more than all other microcomputers combined.
The Commodore 64 software and hardware was not interchangeable with other computer models. It did not matter whatsoever.
Tesla now has more than one production line making identical battery packs. Like the C64, there's no reason to make the parts of those packs interchangeable. That would only make them more expensive.
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2011 Honda Insight + HID, LEDs, tiny PV panel, extra brake pad return springs, neutral wheel alignment, 44/42 PSI (air), PHEV light (inop), tightened wheel nut.
lifetime FE over 0.2 Gmeter or 0.13 Mmile.
For confirmation go to people just like you.
For education go to people unlike yourself.