What is the presumed reason why the venom is sometimes characterized as comparatively mild?

Answer

The typical small size and lower venom yield of an average encounter

The relative mildness may stem from the typical small volume of venom yielded by an average encounter, rather than the toxin itself being chemically weak.

What is the presumed reason why the venom is sometimes characterized as comparatively mild?
PoisonreptilePacificsnakeRattlesnake