My understanding of the tolling framework is that it guarantees a certain return to the operator. The higher cost of building the expansion and operating the pipeline means that the tolls have to be higher, ultimately, for the users of that pipeline. Cost increases have to be passed on, at least partly, to the users. It increases the cost that oil producers have to pay to use the pipeline, and that probably leads to situations such as the one you mentioned.
On November 18th, 2024. See this statement in context.