Cat
Cat reliability operates on a scale best described as chaotically variable. A cat may come when called, or may not. It may use its litter box, or may select an alternative location to express displeasure. It may sleep through the night, or may engage in unexplained running at 3 AM. It may remain healthy, or may develop expensive medical conditions without warning. The cat is a living creature, subject to mood, health, age, and mysterious feline motivations that no human has ever fully decoded. Reliability is simply not a feline core competency.
Towel
The towel offers near-absolute reliability. A towel placed upon a hook remains upon that hook until retrieved. A towel does not wander; does not hide; does not knock objects from shelves or vomit behind the sofa. When one reaches for a towel, the towel is there, performing its intended function with silent competence. The towel's reliability fails only when humans misplace it or fail to wash it, making towel unreliability a human failing, not a textile one. For pure dependability, no household item surpasses the common towel.