However the read-out via radio isn't uncritical. While the traditional bar code can only be read-out optically, that means through direct intervisibility, radio chips like RFID-Tags can be read-out in most cases without without direct intervisibility. This could be a problem when the read-out process takes places unintentionally and unnoticed. Another difference between bar code and RFID is the uniqueness of the RFID-Tag. Using an RFID-Tag, not only the kind of article, but possibly every single piece is identifiable. If someone links together such an unique article with a person, this person can be identified in the following over and over again by the help of the RFID-Tag. Such a linking of bought articles with the RFID-Tag and with personal data could occur, for example, during the payment process with a cash card. In particular charge cards contain personal data.

Another risk lies in the fact that the RFID-Tags are possibly still active after the purchase and also allow an identification afterwards. Some manufacturers even connect the RFID-Tag with their products, so that these are limited without RFID or are not usable at all any more. So the transport companies are able to identify the monthly ticket and its validity through a RFID-Reader inside public transport vehicles. If data is stored centrally, the transport companies have the option to create a movement profile based on personal details without much effort. A good protection against the undesired read-out of RFID-Tags is to remove them from a bought article, if possible. But this method doesn't always work, for example if the RFID-Tag has been processed into the sole of a shoe. Furthermore there are devices, called Deactivators which destroy the RFID-Tags. The RFID-Tag is deactivated and can't be read-out any more, so there is no identification possible via RFID-Tag.