A last mile solution that accommodates all possible use cases would indeed be expensive. One that handles 50% of deliveries? That seems useful. Would 50% be eco

A last mile solution that accommodates all possible use cases would indeed be expensive. One that handles 50% of deliveries? That seems useful. Would 50% be economically viable? What about 10% or 90%? Hard to know and probably will depend on many factors including the local geography. But even if it can't handle 100% of deliveries, perhaps it will be viable for a significant percentage, even if in just limited situations like a suburb with a sweet spot between the cost of adding subterranean pipes and high enough population density to provide high enough volume to justify the capital investment. Very few solutions are able to work for all use cases in all environments. That doesn't mean they can't be useful.