Am in Australia a country that did quite well.
You answer seems very mask focused. Masks are good but my unexpert opinion of why things went well here include more;
- We had strict lockdown early.
- We has free and fast readily available testing. Generally fast both for walk in and get swabbed plus results back in less than 24hr both times I had a cold so got tested.
- There was restricted travel, so states locked themself off from other states. This I feel had a double effect as some state leaders were US style 'cant hurt the economy' and trying to keep things open. The lockdown states essentially erraticated covid and went back to normal while keeping the other states with covid locked out. This put pressure on less strict states to deal with covid more effectively + stopped them spreading across the country via their lack of containment.
- Keeping covid levels low allows contact tracing teams to work effectively on mini outbreaks and be effective. Essentially once overwhelmed govt can't deal with the issue well.
- We have fast and short lockdowns as soon as there are any cases to restrict spread, these lockdowns tend to be regional or state so only parts of the country are effected.
- Our population has largely supported government. Recently my state of QLD had a lockdown and people distanced in shops and wore masks without question or complaint for about 2 weeks even though there was only a handful of cases. Now it's gone and life is normal. These people online that scream about govt trying to control you seem so stupid... Deal with it quickly and you are more free.
Anyway, loads more detail and while I agree masks are great tool for COVID, I think the lockdowns, testing, keeping it under control initally and fast reactions are worth recognising as key components.