I can't read the whole article because paywall, but the answer is because it goes bad quickly and is too soft for easy commercial-scale transport.

Because one only grows randomly in the world once the previous user dies, duh. Science has only figured out how to make zoan fruit artificially.

Cuz they ain’t never heard of it

https://archive.is/jxG6C

Because...

Now when you pick a paw-paw or a prickly pear And you prick a raw paw, well, next time beware