I don't know what Chinese strawberries are like, but I always figured that American strawberries are watery and sour because they're not only big, but they're also grown too quickly for flavor to develop. I think they're engineered to artificially mature early and are basically still unripe.
It's really weird to me that people are generalizing this by nationality. Sure, a lot of supermarket strawberries are terrible. They also frequently (but not always) come from outside the US. Some are ok, and some people get flavorful ones somehow, because I've had excellent quality ones with dessert in a restaurant. Also, there are farmer's markets and stands, even though I'm not in the habit of going to them.
Yes, local in season fruit is always tastier. I suspect because out of season fruit has to come from further away, meaning it has to be picked before it normally would be if it didn’t have to travel so far.
I too have had this experience. Now I always sample one from a pack before I buy. I used to feel guilty doing that, but the quality varies so much and I got sick of wasting fruit purchases when they turn out to be sour or gross. Same with grapes and blueberries from Costco.
