A lady customer bought a cabbage from a well known leading supermarket and claimed it was rock hard, did not look real, suspiciously stiff , hard to cook, had a strange plastic smell about it and when she set it alight smelt of burnt plastic.
It also looked perfect with no holes in any of its leaves.
My view is the cabbage must have been sprayed so many times with, herbicide, fungicide and insecticide that it has built up a residue film on it making it rock hard and plastic like.
The great thing about growing your own is that you choose what is applied to your plants.
If ever you find any puncture holes on any of the leaves of the plants that I supply than that is your assurance that they have not been highly sprayed or even not at all in the growing process.