Adblocker apps/extensions don't require that assurance. The user requires this assurance, and if the browser ignores the user's wishes, the browser is the application that should be held accountable by users.
How is the user to know if it's the AdBlocker or the Browser though? It's a he-said-she-said kind of situation with the AdBlocker and the Browser potentially pointing the finger at each other.
This setup gives the Browser/Maker plausible deniability when they act badly.
This setup gives the Browser/Maker plausible deniability when they act badly.