There may be other issues with the matza machine, like the rolled-out dough traveling through warm areas before reaching the over, which may hasten the process of chimutz. Also, I’ve never seen either type of machine–is it possible that a tzitzis tying machine has a greater role for the operator than the matza machine?
About the difficulty in eating a kezayis of matza vs challah–remember that on seder night we eat four kezaysim.