Probably because it would have to be picked green so as not to spoil before it got to market in the US.
Canned is probably better anyway as it is canned when ripe from the tree rather then having to ripen after being picked.
I’ve always wondered what it’s like, and why they keep it sort of locked behind a counter, instead of on the shelf. Is it really that wonderful?
They keep it in the same place they keep various medicines, liniments, vitamins, male-enhancement potions; and you have to ask someone to get it for you.