This is how the world ought to work. In a while, people will say THIS country did a smart thing, THAT country made a huge mistake.
The “herd immunity” works good with vaccines where no lives are at stake. However when you have live fire, and have to sacrifice your Dad or Grandmother for the sake of “herd immunity”, the theory is not so appealing.
Countries need to make decisions based on their own culture and demographics. Sweden isn't taking "no action". They have cancelled public events, banned gatherings of 50 or more and closed some schools in an effort to "flatten the curve". With every country around Sweden closing its borders, Sweden's borders are effectively closed, along with restricting travel from countries outside the EEA. They are preparing to increase restrictions, as infections are growing faster than acceptable. They are telling their citizens to act responsibly and tightening restrictions when they don't. I suspect at some point, they will get much more aggressive in Stockholm, while allowing other areas more freedom. This might work in some parts of the USA, but would fail in many areas, particularly in cities. Actively managing an epidemic in a country of 10 Million is not the same as in one of 330 Million.