Why?
They are never hot and always cleaned after use.
I thought they were considered as glass.
See Laws of Koshering: “Glass, plastic, glazed china, glazed dishes, Corelle, Pyrex, Corningware, or glazed earthenware do not need any Koshering, since they do not retain any flavor.”
Also : Plastic utensils
Here raCHDal advises I can use them on Pesach Plastic Click Clacks
Here AA advised even if used for hot still OK for Pesach: Tupperware, Plastic reusable cups, ceramic mugs