"By the way the way Americans view the constitution as some sort of divinely bestowed natural law document is highly unusual."

In addition to the US:

Canadians have constitutionally guaranteed freedom of expression.

Article 10 of the EU's convention on human rights guaranteEs freedom of expression.

The UN Universal Declaration of Human Rights has a section of freedom of expression.

Freedom of speech is guaranteed by Chapter III, Article 21 of the Japanese constitution.

Seems it's more common than not in modern countries.