Why is the *exact* appearance of a Zuchon not standardized?

It is a genetic lottery due to hybrid nature

Unlike dogs with established purebred standards dictating precise conformation requirements, the Zuchon is a crossbreed, meaning its physical outcome is inherently variable. This variability means the resulting look is essentially a 'genetic lottery,' dependent on which parent breed's genetic markers happen to be more dominant in any given puppy. Consequently, one litter might exhibit puppies leaning distinctly toward the Shih Tzu appearance, while others might look more Bichon-like, or present a blend that differs significantly between individuals. This lack of standardization emphasizes the importance of selecting based on observing the parents or relying on reputable breeders who track the lineage to manage expectations.