Then you saw a set of images curated to support a specific narrative not representative of the larger group.
I live in Seattle and visited CHAZ/CHOP. While most protestors had masks, a large number of them had the mask below their nose and frequently not covering their mouth either. Nobody curated what I witnessed firsthand.
I think the biggest difference is the protests skewed young and motorcycle rallies skew boomer.
I have zero data to support this, but I've thought about it a lot and it seems to me that the majority of respiratory droplet secretion would be through the mouth during vocalization as a result of the vocal cords vibrating.