> It's very irritating talking about whatever hyperloop is, because that the bar for what the hyperloop is keeps changing (Is it tunnels? Is it in a vacuum? If there's no vacuum isn't it just a tunnel? Is it your own car or a pod? There's solar panels somehow?).
The Hyperloop concept is exclusively a pod in a vacuum tube. The electric cars in a tunnel concept is called the Loop (no Hyper), and it's a different idea entirely developed by Musk's Boring Company (which in turn has no involvement with Hyperloop development). The names are very similar, which has caused a lot of confusion, even in mainstream media reports.
Even for hyperloop, the level of evacuation of air from the tunnels is an optimization problem. It's a question of where exactly is the intersection of cost of reducing the air pressure further vs. gain from being able to further increase pod speed.
Of course with no evacuation you're left with just a train in a tunnel, so I'd argue the defining factor of a hyperloop type transport is that at least partial evacuation of air from the tunnel, with a mechanism for preventing pressure buildup in front of the pods is the main defining characteristic.
The Hyperloop concept is exclusively a pod in a vacuum tube. The electric cars in a tunnel concept is called the Loop (no Hyper), and it's a different idea entirely developed by Musk's Boring Company (which in turn has no involvement with Hyperloop development). The names are very similar, which has caused a lot of confusion, even in mainstream media reports.
I mostly agree with the rest of your comment.