The $2 million/mile number is misleading, since Boring Co only includes the cost of tunneling itself, but public projects usually fold in all of the other costs

The $2 million/mile number is misleading, since Boring Co only includes the cost of tunneling itself, but public projects usually fold in all of the other costs related to the project into their per mile figures. Generally, the actual cost of tunneling depends on the soil and route conditions; for example, most subways are tunneled under existing infrastructure and buildings and thus the process of tunneling also includes numerous measures to prevent damage to existing structures. Urban tunnels must also contend with undeclared but still utilized utility and power lines which must be rerouted. Additionally, businesses and residents impacted by the construction are usually compensated for harms caused by the construction (i.e., excess noise, loss of accessibility, etc.) When you're tunneling under a city it's going to be expensive, and that's generally where you want to tunnel because that's where people actually want to go. The Vegas tunnel has avoided that so far because it's built under a low-use private road), but that's going to change when it has to go under the Strip and under the Casinos. They're suddenly going to discover why public transportation tunnels are so expensive. Note that the LA Metro subways (specifically, the current Purple Line Extension) cost significantly less than $1 billion/mile where they get to tunnel under roads, but more than $1 billion/mile where they are tunneling under buildings or near the tar pits. Similarly, the "Regional Connector" project was ahead of schedule...until it ran into undisclosed utility lines downtown and had to spend a year rerouting hundreds of unmapped utilities lines.