If I understand the question correctly, you want to know why passenger trains do not have priority over freight trains.
As I referenced earlier in my comments, I think that in the corridors, in the Quebec City—Toronto area, there's a recognition that a dedicated passenger line is needed, for economic and safety reasons. The high-frequency rail project is being advanced to do that, and that would address the issue in the corridor.
Outside of the corridor, the infrastructure is owned by the railways, the main ones being Canadian National and Canadian Pacific Kansas City. They're the host railways, and they have agreements with tenant railways like Via Rail and others to use their infrastructure, subject to those agreements and conditions.