Dog
The domestic canine demonstrates extraordinary consistency in its primary function: companionship. A properly socialised dog will greet its owner with enthusiasm regardless of the owner's professional failures, romantic disappointments, or questionable life choices. This reliability extends across a lifespan averaging 10-13 years, during which the dog's affection shows no measurable depreciation. Studies in Anthrozoology confirm that dogs recognise their owners after separations of up to two years, suggesting a loyalty that defies temporal boundaries.
However, the dog's reliability comes with notable caveats. Veterinary emergencies arise unpredictably. Behavioural issues may develop without warning. The dog cannot be stored indefinitely and will, eventually, require attention whether convenient or not.
Tacos
The taco presents a fundamentally different reliability profile. When properly assembled, a taco performs its function with absolute predictability: it delivers precisely the sensory experience its ingredients promise. There are no mood-dependent variations. A carnitas taco does not sulk, a fish taco harbours no grudges, and a birria taco will not develop separation anxiety. The taco's performance is entirely predictable from the moment of assembly.
Yet this reliability proves temporally limited. The taco exists in a state of inevitable decline from the moment tortilla contacts filling. Within 15-20 minutes, structural integrity begins to compromise. The taco cannot be relied upon tomorrow; it must be consumed or accepted as lost. This ephemeral nature represents a significant reliability limitation.