Following statements are extracted from Puri, Sharma, and Kalia's Principles Of Inorganic Chemistry book:
In all hydrogen compounds (except hydrides of active metals), the oxidation number of hydrogen per atom is +1.
In all oxygen compounds (except hydrogen peroxide and other peroxides and superoxides), the oxidation number of oxygen per atom is -2.
Have Chemists tested the oxidation state of every compound (of hydrogen, Oxygen or any element considered to have fixed oxidation sate) in the universe, to say all the compounds (with few mentioned exceptions) of the considered element to have the fixed oxidation state?
Is there any proof or law for supporting above statements? Or is the author sloppy in not saying "In all the known hydrogen/oxygen compounds"?