Arduino RFID-RC522 can't read all rfid cards
RFID tags have a working frequency (RFID-RC522 is 13,56MHz) and protocol RFID-RC522 can read Mifare tags.

Most likely problems: 
 - The RFID scanned uses another frequency (125kHz for example).
 - The RFID scanned uses a different protocol.

There are different RFID tags, frequencies and protocols. There is no one size fits all.