Still, only one family I know thinks it is outright shtus but because it’s so easy to do I think they do it anyway (just as I do).
I am against this practice. There is a halachic reason to tovel, and from what I understand plastic does NOT fall into it. Perpetuating this will most likely mean that the next generation will say its assur to use something plastic if its not toveled! We should follow halacha, and not things that are done because no one knows. Why not just ask your Rav?