According to the Universal Postal Union: A postal ID card is the most widely accepted means of identification in postal transactions worldwide. Generally, banks and other financial institutions honor the postal ID as proof of identity in their transactions.
In the Philippines, a postal ID is a government-issued ID that is one of the easiest and fastest to obtain. People use it to show as a valid proof of identity and address. Therefore the postal ID can give them access to a range of public services.
The postal ID card is a primary form of identification for many Filipinos, without any requirement such as driving skills for Drivers License, travel abroad for Passport, passing a licensure exam for PRC ID, or employment for SSS and GSIS ID.
The basic difference with other Philippine government IDs is ANYONE can apply for it. It is socially inclusive.