Though someone might have another story to refute this, in my entire lifetime I have never come across “white” (i.e., green) seeded grapes. It seems like they are always seedless. Why is this so?
Thank you in advance to all who reply 
White wine grapes have seeds in them.
The white seedless grapes you’re familiar with, in American grocery stores, are table grapes bred especially to be seedless. The vast majority of them are a variety called Thompson Seedless. But there is such a thing as seeded white table grapes–Edelweiss.
So “white” does not automatically equal “seedless”.
I remember my mother getting white grapes with seeds in them when I was growing up (in the 80s). They were fairly easy to find around here. I don’t know whether they still are, as I never buy grapes for myself. They did look different than the seedless green grapes, though. They were more spherical (whereas the seedless ones were more oblong).
White grapes over here (tiny Northern European backwater) sure have seeds in them. At least most of them. You only have seedless ones? You Americans sure are an odd bunch.
Huh, I buy white grapes in the supermarket here in the Netherlands and I’ve only ever found the seedless variety. Maybe you get local grapes in your tiny backwater, Peak? (Although I can’t think of anywhere in northern Europe that grows table grapes commercially…)
IIRC, there are some sorta-domesticated grape varieties in the US (people grow them in gardens and for arbors etc. rather than for commercial sale) that have seeds but are white/green rather than purple. (Or maybe I’m just eating them before they’re ripe. Mmmm, I loves me some sour sour new grapes. :))
Seedless grapes are mutants, and having no seeds can only be propagated by taking cutttings (cloning). Seeded grapes tend to taste nicer (there’s generally a tradeoff between taste and convenience), though there is more spitting involved.
When shopping for 'em, you’ve got to make sure they’re seedless, even here in the USA. I’ve gotten many batches of white grapes that weren’t seedless. It was always an accident, since I used to assume that same thing, that all white grapes were seedless. Heh – they’re not.
Can’t get the seedless variety in France (unless you go to the very upper crust supermarkets and pay thro’ the nose!).
I’m not so sure. I’ve read they’re treated at a certain stage of flowering in order to prevent the seeds from forming.
Call around and ask for “Green Globe” grapes.