The Fallacy of Rubber Stamps in Document Authentication
A common fallacy that people have, perpetuated by our government, is that a rubber stamp makes a document authentic. It costs Rs. 100 to make a duplicate stamp. If someone were to commit fraud of any kind, an extra Rs. 100 to be spent is small change.
Purpose-Driven ID Card Structure
The intended purpose of the ID card is going to drive its structure. If it's only internal, then even without a rubber stamp, it can be authenticated (by signature, photo, etc.). One of our clients has a barcode printed on the ID card. The guard scans the barcode, and the original data, including the photo, appears on the screen, which needs to match the photo on the card and in person. If security is not a big issue, then such an elaborate arrangement is not necessary.
Stringent Requirements for Third-Party ID Proof
If the idea is to have it as proof of ID for a third party, the requirements need to be more stringent.
To answer your original question: a rubber stamp actually adds nothing, especially in the case of laminated or preprinted cards.