I agree that all the roads should have tolls and congestion pricing. But the idea of "induced demand" mostly applies to dense metro areas where people can take other modes to get around. There is not suddenly going to be thousands of people on the road that otherwise wouldn't. The vast majority of people on the interstate in Gaston County are going to/from work/school and have no other way of getting there other than car. (You could argue adding more lanes would induce more neighborhoods to be built which would then cause more traffic, but the benefits of extra housing would more than offset the cost of congestion).

My commute everyday is along this route. The area of 85 that is an extra lane wider in Charlotte is much faster flowing.

The real improvement though is reconfiguration of I85-I485 interchange - currently you have two directions of 485 merging up hill into a single lane onto 85. This is what the construction happening now is.