This is typical in the art world - crime lord or otherwise. Art is often kept in freeports - storage facilities that exist outside of the realm of domestic taxation. This allows the artworks to be sold without incurring taxes or customs. Many artworks pass through owners who never actually physically lay eyes on them, and many pass through multiple owners without ever physically moving.
For a lot of people who transact in art, actually looking at the art is not at all the point of the exercise. Speculation on the art is the whole point. These things are effectively fanciful, convoluted, tax-dodging securities instruments, with only the most cursory nod to the appreciation of art.
Which, y'know, is awfully reminiscent of something else in recent memory...