They are not at all. In fact, the way to eat these types of grapes in Japan is to peel off a little skin, then push and suck the inside of the grape into your mouth. That way you avoid eating the skin which can be a little bitter.
It may be a bit short of world class, but you could do much worse than Palisade, Colorado (among scenic mountains along I-70, about 8 mi east of Grand Junction). The season is roughly early July through early October.
It’s probably best known for peaches, but cherries, apples, pears, plums, grapes and apricots are also found there, and typically excellent. You can enjoy the fruit fresh, or at one remove (wine / honey) or at two (mead: wine made from honey).
I was just going to mention Costa Rica. I’ve never been, but an on-line friend of mine is building a house there now, and posts about the fruit a lot. (And tge orchids—dude is obsessed with orchids.)