There is no doubt that error born of ignorance is one of the acknowledged causes of language change. However, from a purist’s point of view––which happens to be that of Y-H-B––ignorance of the law (alias code = language norm) should not be an excuse in this age of mass literacy.
Notwithstanding, errors are rife. For instance, in the American media it is common to hear the erroneous phrase “under someone’s watch” for the normative “on someone’s watch.” Such errors are testimony not only to the difficulty language users encounter in sorting out the variety of prepositional phrase abounding in English but to plain ignorance as to which preposition governs which noun. Sic transit gloria linguae americanae!