Bulkfreighters only bring BACK food to their home port. If you want to deliver food, you've got to use Merchants.
But I do agree is difficult to address shortages, the pricing of commodities should fluctuate more when a colony has 0 amount of resources compared to maximum amount of resources. And merchants do not always pick the most profitable cargo for a particular destination, though they're supposed to. I'm sure Dave is working on it.
That's simply not true, while the Bulkfrieghters are carrying mostly steel, they also have food in their compartments to deliver, just not as much as I would like. The issue would seem to be the fact I use circular routes for trade. Just created a bulkfreighter fleet and directly click on of the planets, and it grabbed a full food load. However if I then set the fleet on a circular route to the same planet, it changes its load to steel.
Don't know how to handle this, I can't afford the ships to just wander around, they always seem to end up heading to a enemy planet and getting blown up, but they are pointless if they can't work out what to take on the route properly.