It's not the virus that the masks stop. It's the water droplets in which the virii reside. Masks stop some of the droplets completely and slow down the others so they tend not to travel as far.Our last trip was in August 2020 to Whitefish on the EB. For common courtesy we did wear our masks when moving about the train but the train was loaded with Amish travelers few of whom had them pulled up, and many were mask free. While masks are good protection against bacteria there is evidence to suggest that they offer minimal protection against virus microbes that measure millionths of an inch. It is what it is, and by 2022 I believe that masks will be a thing of the past.
When compared the size of even bacteria, water droplets are huge boulders as evidenced by the fact you can see them when someone is sneezing.