To a snake, biting a human is often just a last resort and even then sometimes it may choose not to waste that precious liquid and reserve it for more important things like catching prey
Snake venom isn’t designed for punishing people. It’s a precious liquid for snakes used for survival. Snakes rely on it to hunt and because it takes time and energy to produce, they don’t use it carelessly.
When a snake bites a human, it’s usually acting in self-defense, not because it enjoys it or wants to.
In some cases it may even hold back its venom entirely, delivering what is known as a dry bite.
More of a warning.