Vietnam banned international inbound travel without a 14-day quarantine and extinguished local transmission via test and trace. These are both very good ideas and both impractical for the United States.

The former is a logistical nightmare in a collection of states that basically is not possible to carry out due to our incompetent government and the scale of international travel in the US being several orders of magnitude higher than Vietnam's per capita (and gross rates of course) and the latter won't work (and hasn't worked when we tried it) because our population is inherently distrustful of our government(s) and generally have the right to be that way.

Again, not all tools smaller countries have are available to larger ones, and vice versa (America/EU/etc have better access to vaccines as a plus, for example).