Konda

Of course there are a lot of other factors, like the size of the countries, their healthcare systems, their preparedness (excessive testing and contract tracing) and how disciplined people are

But as other people said, even if it only helps a certain percentage it still can have a huge impact.

Also you don't just wear it to protect yourself from not getting it, a big part of it is if you do have it (but are asymptomatic) you are far less likely to spread it to others. That's the biggest help of the masks which most people in the west don't think about, most think it's to protect them, but the main thing is to protect others.

In Asia it's very common to wear masks when you are sick, usually people mainly were masks to protect others.