There is really low number of infected people and also low density of people walking outside in Czech republic. I am not sure you can make a lot out of it. I think requiring face covers outside is more panic than reasonable measure.

I live in Prague and when I go outside I meet someone once in few minutes and majority of the people are not wearing face cover despite it is required. Mostly they have it prepared on the neck to put it on when they go inside. One doctor in TV did not recommend extensive usage of face masks as cheap or improvised masks tend to get wet after 20 minutes. This significantly reduces their effectiveness. Risk of being infected outside is really low unless you are in crowded area.

I second that request for a source. It sounds like disinformation to make people upset.