It is very possible that during assembly, the pieces were missed.
Try to see if you can shift the seat-stay or chain-stay sideways on the pivot. If you can, you definitely need to find another bushing to fit in there.
If there is sideways play in that pivot, it will wear out prematurely. You'll also get all sorts of dirt and debris stuck in there, which will also wear out the pivot much quicker than if it were covered with a bushing.
Another thing you could do is go to a brick and mortar store that sells the same brand of bike and see if the bikes in the store are also missing them.