Because it is far more perishable than the other condiments? ? ?

I would not want to shoot a stream of "past it's due date" sour cream onto my fresh food. I would like to be able to see and smell it prior to deciding to eat it.

The problem with any product you squeeze out a bottle is that its viscosity has to be modified to allow air back in the bottle for the next squeeze. There is sour cream in a squeeze form, but its really lame. A better way to dispence highly thick items is to have a seperate inlet tube with its own one way valve. That way, when the bottles is inverted and squeezed, product is forced out the opening, upon release, air is drawn in thru the inlet tube, and the process is repeated. No muss, no fuss. I have made several of these (as prototypes), and its sorta like a "machine gun" for condiments.

I would think it would be better to have a collapsing tube, like a toothpaste tube, that doesn't require air to go into it. Air entering the container is likely to contain mold spores, which will greatly speed the sour cream spoiling.