[whylah]

I’ve encountered some with their masks down and talking to one another. I’ve interrupted their conversation and tell them to mask up and they obediently followed my requests. My phone is ever ready to snap a photo as evidence to submit to SPF and LTA.

Not many will dare to tell them to do so.
In such confined space, I think it is in everyone interest to wear the mask properly and avoid talking if possible, or at least not to talk loudly. Unfortunately, not everyone believe it.
Thus I believe the solution is to have proper enforcement.