Gregory's ServerWine grapes can be ugly! They get mashed up into juice.
But table grapes have to be in good enough condition to ship, & for people to still want to buy them when they arrive.
So table grapes are higher maintenance to grow. You'll lose more the crop to un-shippability, etc.
That's one reason there's so much agritourism in the winery business. Often, there's surprisingly little money in the vineyard itself.