Not only that, investing in the electrical grid it is always expensive in any western country. Zoning, environmental, licensing, technical regulations, and the nimby effect, all will add up to the cost. Even if it is just upgrading existing infrastructure it is not easy peasy, and building new grid infrastructure can be hampered by local sensibilities.
From the technical standpoint adding new grid capacity adds also more nonlinearities in the grid system that need to be managed. And, high power electrical systems are difficult beasts to control, it is not like in star trek that one can freely route power through any circuit without regard for transitory effects that can shutdown parts or all of the grid.
From the business standpoint, I think it depends on the business culture. In Europe, non-english speaking countries will invest on its grid infrastructure more regularly ,France, Germany, Spain, Portugal, etc... invested recently or are investing in their grid systems. In the UK and Ireland, it is mostly anecdotal evidence, but it seems they are quite happy to not invest in infrastructure as long it still works.
And, another thing, competition doesn't work on grid systems cause they are a natural monopoly. You cannot have two different grid providers, duplicating that type of infrastructure it is very expensive and difficult to justify. Plus, technically having to manage two grids into a local grid, and have power plants outputting for separate power circuits seems a recipe for more problems.