[soreal]

I checked the table you linked and:

Apple: 38 Banana: 51 Pineapple: 66 Watermelon: 72

vs.

Ice Cream (premium): 37 Sponge Cake: 46 Frosted Flakes: 55 Snicker's Bar: 55

Fruits really are very high GI compared to regular snack foods. They're relatively healthy for other reasons though.

[wpietri]

A perhaps better measure is glycemic load, which takes mass into account. 400 calories of frosted flakes is about 100g. 400 calories of watermelon is 1.3kg. Watermelon's glycemic index is worse, but at reasonable serving sizes, fruits generally end up being way better.

[Programmatic]

You also cherry picked, figuratively speaking. More literally, you didn't pick the cherries at an index of 22. There are a lot of fruits in the 20s to 40s. I tend to stay away from both pineapple and watermelon.