Rubbish. Remember the anti mask protests in Melbourne during lockdown? The messaging was pretty specific.
And I'll give you 2 instances in the last week on pour cruise. An older Australian couple so obviously in a higher risk group. A week ago and on a bus excursion in Italy where wearing a mask is mandatory and must be a proper fitting mask the gentleman was wearing a surgical mask so strike 1 as that is not considered appropriate. Strike 2 was that he had a really suspicious repetitive cough. Strike 3 was that he took off his mask to cough!
Then this morning the woman of the couple had the same sort of cough. Although sitting in a function space with at least 100 other guests waiting to disembark she was maskless. We moved. Reported it but hands in the air as unless seen by crew nothing could be done.
In Australia my guess is less than 50% and probably closer to 20% are willing to test and wear masks. So your aim is not possible.