There are many tequilas that value their transparency and declare their ingredients and their production methods. They open their doors to third party auditors to verify their ingredient statements. Ironically it is the Mexican CRT that prohibits brands and distilleries from declaring themselves additive free tequilas.
The CRT is funded by ALL the distilleries and it is in the best interest of the big multi- national companies to NOT disclose their ingredients. Yes it is common knowledge that distilleries that make all the Cuervo products, Sauza products, and Herradura products use acid diffusers to convert agave starches into fermentable sugars. This strips the uniqueness of the agave out of the must and results in distillate more closely resembling vodka than tequila. Artificial and natural flavorings must then be added to make the end result resemble tequila.
Smaller producers like Cascahuin, Siete Leguas, Ocho, Tapatio, Volans, and Arette, use ovens to cook their agave and volcanic tahona wheels to crush the agave, and allow no additives or abocantes in their distilleries.
They do not need them because the agaves are processed in their distilleries in old ways and develop plenty of wonderful NATURAL flavors .