You are mistaken.
There are four families of toxic white umbellifleurs; Cowbane, Hemlock, Hemlock waterdropwort and Fool's Parsley, and as Xylaria has said, there are several varieties.
It is also a fact that what is common in one area is not necessarily common in another.
Mugwort is 'everywhere' around here, but I was working 30 miles away on Sunday and it's a totally unknown plant to the locals.
I know of only one person, out of the hundreds I know who forage, who confidently names every species of white umbellifleur.
There is another issue, the plants of the white umbellifleurs have a prevalence to cause dermatitis, and cause cattle who graze on them to produce milk that is unfit for consumption.
So, poisoning, dermatitis, difficulty in confident identification and only really four of them are worth eating anyway
Hardly surprising most folks just avoid all but those.
Pignut is good food, hogweed too, and Sweet Cicely has lovely seeds and scents and Scot's Lovage is (well for me) hard to find, but also a pot herb with edible seeds.
All too easy to get the umbellifleurs wrong with tragic results.
cheers,
Toddy