The page you link contains many interesting examples; but many of them are simply cases of making the vote harder -- requiring unanimous consent to change English-French bilingualism in Canada, for example -- rather than cases where the law simply can not ever be changed by a vote.
With regards to Germany, the page says:
...if a constitution provides for a mechanism of its own abolition or replacement, like the German Basic Law does in Article 146, this by necessity provides a "back door" for getting rid of the "eternity clause", too.
It's really hard to have a legal system that literally can not be changed by any legitimate vote -- only by revolution -- because what sits at the bottom of most of them (all of them?) is that the consent of some body politic is necessary and sufficient to legitimate a law.
Ultimately it doesn't matter what the constitution says if a large enough supermajority is unhappy about it. Constitutions by themselves are pieces of paper, they only work when society as a whole chooses to treat them as more than that.
But https://en.wikipedia.org/wiki/Entrenched_clause are not all that uncommon in general.