It would cut into the capital available to commercial banks, so of course it won't happen. RBC, TD, CIBC, BMO and Scotia do not want to lose those sweet customer deposits.
Same reason we don't get public rail and public telecomms: essential services can only be delivered if they make a rich person richer.
I wonder if it would help if we banned fly-by-night couriers that Amazon et al use and diverted more of that volume through CP.
They'd be better-paying jobs, too.