I'm intrigued as well. Have you ever asked a WG, just out of interest? (maybe easier if someone had a WG GF if they're more open about it)
To stephenmozza, I actually do sometimes wonder how much my grocer makes when selling me veg. You can call me a miser or petty or something, but if I weren't curious about many things, I probably wouldn't have started here / mongering. That doesn't make me necessarily a curious person though