To be fair to SP, I feel that they tried to not only maintain, but to also actively develop car load business at times. A perfect late in the game example is Crocker Park in Brisbane: A warehousing/light industrial park which was constructed with a rail line looping through and rail access to most (all?) buildings. The park is a success, the rail part not so much. Rails are gone, a trail remains.
And since our RR's are businesses instead of public agencies, they have to balance their books if they want to stay in business... For any business it is tough to support unprofitable ventures, no?