I'm guessing that you could substitute a piece of appropriately sized drain pipe of some sort as long as it's not dramatically taller (when run along that same path) than the existing broken one.
My guess is that they specified one part for this knowing that some of these dishwashers would be portables (with the butcher block going right up against the pipe, necessitating the squished tube) and some of them would be built-ins. I'd be surprised if your "under counter" is flush with the top of the whole dishwasher. Most have some extra clearance above the top of the dishwasher.
Val