What is the logic behind face masks protecting others but not the wearer?

[trulydelicious]

Say the 3-ply IIR disposable masks sold at Boots for instance.

Intuituively one would think that the barrier in the mask would prevent (to an extent) droplets going out through the mask as well as droplets coming in if somebody sneezes or coughs near the wearer?

In a way this should also work for non-surgical cloth masks (although the level of protection may be lower).

Am I missing something?

I wear masks but restrict where i go and only go to Tesco now.

@HeresMe the reason why "do it to protect others" doesnt wash is that certain quarters wernt particularly bothered when people were dying for other reasons

And the altruism argument doesnt wash when most people have been voting for the opposite for the past ten years.

Even less so when one of the posters most gung ho about masks made derogatory comments about disability benefit claimants.

@helenadove

Most people are cunts I'm actually hoping for a cull in society.