[fowudvwp] Watto

Neither the Toydarians nor the Hutt are actually immune to the Jedi mind trick; they have just been fooled into believing so.

Simpler would be a small conspiracy fooling only Watto and Jabba.  This makes sense, because if the species as a whole were immune, we would have expected to see them having leveraged their immunity to much great effect.

Much grander is a larger conspiracy involving fooling the entire species (but keeping them in check), all part of a grand plan by the Jedi spanning generations.

Tell a story of the endgame, in which the reason for the ruse is finally revealed.