Docs vary a lot on this issue. Even though it's technically free, it's ideally to be dispensed to people with an active infection. I'm sure the government doesn't really want people to have it "just in case", but we were uncomfortable traveling to Canada, on a ship, without it, and with no way to get it. I'm very thankful that I nudged our PCP, believe me.
We are confident that we got infected on a shore excursion. We were on a bus all day--about 35 people--where only 10 of us wore masks. It was a wet, rainy day. Air circulation was poor. The servers at lunch were not masked and for the first time, we were forced to have 2 table mates [neither wearing masks]. We went to an historic home that was packed to the gills--again, poor air circulation, many unmasked "strangers" passing through rooms--and then to an overcrowded creamery where we had to stand in a long line for ice cream with more "strangers". When not eating ice cream--which we did outside--we remained masked.
We've since canceled 2 cruises that originate & terminate in Canada because of their 10 day quarantine should we be infected again.
When we cruise again, we'll embark & debark in the US and we won't go on any excursion that requires an enclosed bus, a common lunch where we have to sit with others [especially inside], or a venue that is small/tight that will be crowded with other tourists.
We did everything the way we should have, short of not going on the cruise at all and/or not going on any shore excursions with others. We masked everywhere, including public restrooms, ate outside, used the stairs most of the time, etc. It's a real crapshoot with the super infectious circulating variants, & we lost this round--and it's infuriating at this point, 2.5 yrs. into this cluster.