A person has lived their life under the EU rule. They know what's what. And how it's affected them.
How has it affected you then?
I'd imagine most people have no real idea how the EU has affected them - I include myself in that. Without sitting down and spending far longer than I'd like doing research I couldn't tell you exactly which things that have had an effect are because of the EU and which are not. Sure, I know bits, but not everything.
It's simply wrong to say everyone who has lived in the EU must therefore know what it's done and what it hasn't done that's affected them.