It's an international standard with 196 countries. It's difficult to get 196 countries to agree on anything. There's now a chip in almost every passport, but

It's an international standard with 196 countries. It's difficult to get 196 countries to agree on anything. There's now a chip in almost every passport, but the paper version provides great backwards compatibility for places where there is no Internet or the Internet is unreliable and they still need to control the border. For other places, countries make bilateral agreements that eliminate the requirement for the book, such as the passport card and nexus. Biometric only has a lot of annoying edge cases. What happens if you're severely burned and then need to cross a border? Biometrics aren't going to be able to identify you, but if you're in possession of a passport that hasn't been reported stolen, and eye color, height and weight all match, they'll let you through. Similarly, a passport issued to a newborn is not going to get a biometric match on a four year old kid, but if they possess the passport, eye color, and approximate age match, and they're traveling with their parents, they'll be let through. The possession of the document lends significant evidence that the traveller is who he/she says they are.