Some local plants might be edible and even delicious, but they are either way to costly to grow or harvest, or they are nigh impossible to preserve. Or they simply are edible, but not sustaining, like sucking nectar from stinging nettle blossoms.

Some are acquired tastes like e.g. turnip tops. You could probably harvest tons of them, but there is no real market for it.

Or take edible flowers, you basically can't preserve them, and all you can do is put them on a dish for decoration.

Pearl Onions are a borderline case, for example. Between harvest and sitting in the pickling juice they only have a few hours (3-6, IIRC), or they are a case for the compost heap.

A lot of Lebanese shops sell sorrel. Sorrel is just clovers. 50% of people setting this meme are 100 meters or less from sorrel right now.

Getting an allotment, so soon I will be able to grow things I don't normally eat because they are expensive or aren't sold in shops here.

Cultivation takes a couple of human lifespans.