My understanding was that it was genuinely uncertain early on whether it was being spread in large respiratory droplets, and therefore whether there was a higher chance of spread via surfaces/touch, or if it was being spread via aerosolized droplets. These are two different transmission vectors that would react differently to masking by the general public. On the other hand, my understanding is that some governments were slow to recommend masking even as it became clear that Covid was airborne and that masking would decrease transmission, because of concerns about supply.

I’m a little fuzzy on timelines, though, and I don’t have any sources so take this comment with an enormous grain of salt.