I am not a lawyer so sorry if this is obvious, buy how can a country been the use of software that is made in another one? I read country X is trying to ban Y,

I am not a lawyer so sorry if this is obvious, buy how can a country been the use of software that is made in another one? I read country X is trying to ban Y, and every time I just wonder: how? I can download something off GitHub (except if the ban is in the US), or a copy somewhere else. Ideally, developers wild set a multi country repository with a canary and be done.