Musk isn't selling a better TBM. He's selling an entirely new transit system. Well, an entirely new transit system that sounds very much like personal rapid transit and shares most of the disadvantages with PRT and adds a few of its own (such as focusing on supporting cars).

If Musk were selling better tunnel boring, what you would see is attempts to subcontract on major infrastructure projects. This bid is for an express "rail" system to O'Hare from the Loop, and the intent on Chicago's part is to make The Boring Company suffer all the risk of construction and possibly even pay for the entire thing (Chicago did previously have a construction plan for an express rail to O'Hare, but it was nixed due to cost overruns).