Power lines have their own capital cost, and take years to build, and obtain land and permits for, and have power loses ranging from 8 to 15%. Most major powerlines are at their limit because of a variety of reasons, including the process to recoup the cost of building them, once created.

https://blog.se.com/energy-management-energy-efficiency/2013/03/25/how-big-are-power-line-losses.