Anti-theft: Really?

“Anti-theft“ as defined by Random House Kernerman Webster's College Dictionary (2010) means “preventing or discouraging theft”. The American Heritage Dictionary of the English Language (2000), 4th. Edition, defines, as adjective, anti-theft as “designed to prevent theft”. Collins English Dictionary – Complete and Unabridged (2003) defines anti-theft as (of a device, campaign, system, etc.) designed to prevent theft.

But, what if the said device is also subjected to be stolen by thief? Or taken by someone... Then there will be no more “anti” theft. Is it true?