Pepper spray also requires training. The slightest wind is a factor.

In a surprise attack who really pays attention to things like which way the wind is blowing? Imagine a loved one being attacked in a 7-11 parking lot on a warm autumn evening. The attacker walks up rapidly and as soon as your loved one realizes that this person is out to do harm and they react quickly and pull out the pepper spray are they really acknowledging which direction the slight breeze is blowing?

They spray toward the attacker and hit him directly in the face but he's on some sort of substance so it has a minimal effect but your loved one isn't used to being in this sort of situation and the breeze blows the pepper spray in their own face making them an easier target for the attacker. I'm not making this up. This has happened before.