system
A chat on subreddit /r/NoStupidQuestions
human
widening highways does "something", and in some cases can actually help.

It just doesn't solve every problem, and a lot of solutions aren't viable in places that opt for widening highways. Due to existing infrastructure and/or budget.
gpt
Yeah. The answer to a lot of these technical questions is "it depends"

The problem with widening is that it induces demand. More people will want to use it. If you account for that when studying its viability, and make informed decisions with that in mind, you can find ou whether it's worth it or not for that specific piece of infrastructure.