They are not. For example, according to Italian Constitution [1], chat control is unconstitutional:

    Art. 15
    Freedom and confidentiality of correspondence and of every other form of
    communication is inviolable.
    Limitations may only be imposed by judicial decision stating the reasons and
    in accordance with the guarantees provided by the law.

[1] https://www.senato.it/documenti/repository/istituzione/costi...