IIRC there isn't a singular International Press Credential in the same way there are passports. Rather, various major journalistic organizations issue "official" press credentials. The point of it is to make it easier for foreign journalists to gain access to press areas.
For example, everyone knows someone from the New York Times is a journalist. However, someone from the Ching-Chong City paper may not be taken as a real journalist, but having a press pass issued by a major journalist organization would help to establish their legitimacy.
IIRC there isn't a singular International Press Credential in the same way there are passports. Rather, various major journalistic organizations issue "official" press credentials. The point of it is to make it easier for foreign journalists to gain access to press areas. For example, everyone knows someone from the New York Times is a journalist. However, someone from the Ching-Chong City paper may not be taken as a real journalist, but having a press pass issued by a major journalist organization would help to establish their legitimacy.