I can only speak to the purpose of this new measure in Bill C-52, which is to provide an extra tool for shippers beyond the tools that currently exist in the act for shippers to be able to seek the level of service they would like to have from the railway.
Evidence of meeting #66 for Transport, Infrastructure and Communities in the 41st Parliament, 1st session. (The original version is on Parliament’s site, as are the minutes.) The winning word was shipper.
A recording is available from Parliament.