This is ancient technology, literally over a century old.
https://en.wikipedia.org/wiki/London_Post_Office_Railway
No need to name-drop the Boring Company, as it's just a marketing company who bought a COTS tunneler.
Nothing that this company presented was novel. The critical aspect of putting together an railway network through tunnels is a) it's collosal construction and maintenance costs, b) property rights.
The numbers of putting together a tunnel network hardly add up, and ultimately projects fail because there is no way to make the numbers work unless you expect to fleece local and central governments.
It's also quite strange that CST's marketing brochure does not mention at all two of the main solutions to p2p logistics in urban environment: hub and spoke model with the last mile delivered with small electric cars/scooters/bicycles (Amazon already employs this heavily), and drones.