You still have to get lithium?

Lithium is reasonably cheap already, and is in that stage where a marginal increase on scale brings the price lower, instead of higher.

I’m not a chemist — would it be harder to get it from recycling old batteries than getting it from rocks?

Because even the battery market is saturated, recycling is the only source you’ll need.

There is a lot of lithium about, just not a lot of stuff that is easy to get at. The cost of lithium isn't a huge part of battery cost at the moment anyway (10s of dollars per kilo with about 50kg in an ev battery).

About 1kg/kWh?

more succinctly: petroleum is a consumable needed for operation, lithium is a manufacturing input

It wouldn't make sense though, because economies of scale are enterprise-wide not industry-wide.

I don't know that I'd agree with that. Look at the computer industry, for a example, and how many small, medium, and large agents all benefit from what amounts to a distributed economy of scale. Apple, Microsoft, Dell and the like all produce better products with less investment when their suppliers can spend fewer dollars per widget throughout the supply chain.

They happen on both spheres.

But yes, I would really like to know the rationale behind the GP's opinion.