Well, I don't know . .
Bell peppers and eggplants aren't particularly deadly, though opinions may vary on certain "high end" chili peppers.
Even the black nightshade has been used as pie filling and such. You just have to simmer it for a long time. That's why tomato sauces were originally cooked for a long time in Europe. Tomatoes are so obviously nightshade berries people just persumed they were poisonous and treated them according to normal practice.
Of course, the deadliest of all nightshades for people who actually die from it is tobacco, but all those people would probably have died eventually anyway.
According to the Macrobiotics folks (Michio Kushi school), all nightshades are 100% terribly awful and should never ever be consumed on pain of disease and lingering death. Heavy consumption of potatoes, however, does not seem to have materially depleted the population of Ireland, and I myself have eaten entire flats of tomatoes in just a couple days - and lived.
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