We finally have an answer: The beginning and the end of the sliding motion that produces static electricity experience different forces – resulting in a charge differential between the front and the back that results in the crackle of static electricity.
So the generic “particles just rubs” in the texbooks were lies and they didn’t know shit?
We knew enough to make it extremely useful, but didn’t have a full understanding of the underlying mechanics.
Hate to break it to you, but that is how knowledge works. Even things we have an extremely detailed understanding of are likely to have underlying mechanisms we are not aware of.