I take it you have never been to mountains or driven through rural areas? Cell coverage is line of site.

This is because the extra lane allows demand to change. It is not congested so people feel ok building and moving to further out suburbs. This continues until demand has increased to cause delays.

Note that Houston and Paris have about the same population. Paris is 1/3 the size. They are actually removing a lane from their loop highway and planting trees, and turning another lane into busses only. Only considering transportation, I would much rather live in Paris.