Cloth masks don't filter particles, nor are they intended to.
Instead, what they do is trap the moisture attached to the virus. Without the moisture, they fall to the ground rather than going airborne. This results in a ~25% reduction of spread if everyone infected wears them.
1) they result in mostly theatre, not common sense use of the masks in a beneficial way 2) enforcement increases spread between the people most likely to exhale the virus and officers 3) trying to force people often triggers a disobedience reaction