I can't specifically speak to mangoes since I haven't tried them in that many places, but melons in the United States are outright terrible in comparison to anything I had when I lived in Japan. They cost more but you're pretty much guaranteed quality. A relatively inexpensive melon in Japan might be about 10 bucks but its going to be as good as the best melon you can get in the crap shoot at the grocery store. When you start moving up in price the melons basically become so good that they are an out and out replacement for any kind of high end dessert. Theres no need for ice cream, yogurt, honey, etc because the melon is just that good.