It's not just a energy cost issue with AGI though. With autonomous vehicles we might not have the technology, but we can build a good mental model of what the thing can look like and how various pieces can function long before we get there. We have different classifications of incremental steps to get there as well. e.g. level 1, 2 and so on where we can make incremental progress.

With AGI, as far as I know, no one has a good conceptual model of what a functional AGI even looks like. LLM is all the rage now, but we don't even know if it's a stepping stone to get to AGI.