I believe it was sugar based products and agree a common gauge may help.
However lets ignore Brisbane for now and look at Sydney. How much intermodal traffic occurs withith 500km of Sydney on the NCL or the Main South? No break of gauge issues here?
That's true...most of the short haul containers coming from regional NSW are for export. However, being the largest consumption centre in the country, the Sydney/Wollongong/Newcastle triangle should absorb a disproportionate amount of consumer freight from the east coast - and that should mean a disproportionate amount of the horticultural and consumer goods produced in Bundaberg should be travelling the 1300km to Sydney - a rail friendly distance elsewhere in the country. I can understand domestic container business struggling against trucks on the NSW North Coast with short hauls available to both Sydney and Brisbane, but the only reasonable explanation for non-existent rail freight out of Bundaberg (even considering the alleged capacity issues south of Nambour) is the absence of a single gauge rail routing to cross border destinations.