With adequate training, workers in a broad range of industries know from experience that they are quite capable of wearing their PPE consistently. And a well-fitting N95 can stop transmission - at this point all but the most fanatical airborne-deniers have accepted that fact.

So all a trial that finds otherwise at the community level can tell us is that the team running the trial did not choose and effectively communicate appropriate protocols for their use. There is no magical property of RCTs that can change that fact.