When you say they don't have 'added taurine', do they list the taurine content at all? I know nothing (or very little!) about nutrional requirements but I just looked on the back of the Bozita pack as an example and it has 'additives' listed as being vitamin A, vitamin D, vitamin E, copper sulphate.
There is no added taurine but listed under 'Nutritional value' is protein and in brackets 'Taurine 0.07%' The Bozita packaging says 'contains all vitamins and minerals your cat needs' so even though there's no added taurine the natural taurine content is enough.