All of these also helped last year's summer, just look at the graphs, we had a very very normal summertime here, people were going to bars, some clubs, all the parks were crowded and we still got relatively very few infections. Now look at the fall-winter of 2020/2021, massive increase of infections when we aren't on vacations mode anymore and have to stay inside.
Sweden is starting to see an increase of delta-variant cases and by living here and seeing how much people just stopped caring we will definitely see a new wave of infections if delta and/or lambda spread and are really capable of evading the current vaccines.
Please, don't use us as an example if you don't have tacit knowledge of how this society and country works, there are seasonal effects in play that, it seems, you are completely unaware of...
Vaccination does reduce the chance of spreading the virus. Having 10% of the country get the natural variant and 45% fully immune, plus still doing the social distancing stuff, and requiring negative COVID tests for those entering the country, seems like a pretty good way of keeping delta under control.
https://www.news-medical.net/news/20210714/e2809cHerd-immuni...
As a comparison point the CDC estimates that about 36% of Americans have been infected.
https://www.cdc.gov/coronavirus/2019-ncov/cases-updates/burd...
Couple that with the fact that the Swedes aren't acting completely stupid and are doing a pretty good job of voluntary distancing (not to mention border control) and it seems like the numbers are pretty easily explained. Quite the cost to get there...