"People are not as good as dogs" is a metaphor, which means that dogs are more trustworthy, more loyal, and kinder than people. Behind this sentence reflects some problems in human society, such as human selfishness, deception, betrayal and other behaviors.
In contrast, dogs' behavior is simpler and more direct. They will not cheat or betray, and are loyal to their owners. . In addition, dogs' trust in their owners is unconditional, unlike people in human society who need to establish a trusting relationship to trust each other. Although this sentence is not the literal truth, it reflects the problems existing in human society to a certain extent and reminds people that they should value and respect the animals around them more.