I believe that the induced demand happens.
I recall decades ago, when they were planning the “Washington Circumferential Highway”, which later was named the “Beltway”, planners expected that this circular road would be a bypass around Washington for through traffic, for the long haul truckers and tourists more than local traffic.
Eventually, suburban sprawl around Washington occurred in areas which were adjacent to Beltway interchanges, and traffic patterns changed because of the existence of the Beltway. Traffic increased precisely because the Beltway was there.
Very few people traveled from Bethesda to Tyson’s Corner in the 1950s. Today that is a routine trip on the Beltway.
The same thing happened in LA and Orange County, California. When Interstate 5 was built through Orange County, it brought large parcels of undeveloped land within easier commuting distance of LA. Land values skyrocketed, and orange groves became suburban housing tracts and shopping malls.
I’m sure many of you can think of other examples of this induced demand where you live.
I always thought widening highways just invoked The Utility Theory Of Work.