In school days, we use to wear our school uniform, along with the badge & identification card. That was not just to add On to our uniform that was beneficial to us as well. Most of the students nowadays, doesn't like to wear their ID cards. Few people think identity card messes up with the uniform. But it is more secure when it comes to safety in any context.
Suppose, any student entering your campus without your permission & you have no idea who they are. In such circumstance, you will get their information only with the help of their ID cards. You'll get to know their purpose of entering someone else's campus. Security team doesn't allow any unknown person walking inside the owned area. It's because of the ID cards which allow you to enter in. This brings security to you.
Another example we can take is, when students are taken to educational trips & picnics, they are compulsorily asked to wear identification cards so that if you are lost or misguided by any chance, others can help you reaching to your right place by identifying your name & school you belongs too. This is again best for security purpose. It is inexpensive also.
Most of the schools & colleges have introduced wearing identification cards as compulsory. Even if you are in uniform & not wearing ID card, it won't bring you security than wearing an ID card over the casuals. Few schools have introduced the new policy that Students and staff must wear IDs at all times when on campus. Wearing ID card is not at all a bad option; One cannot go anywhere without being asked for identification. People will also have more personal interactions and be able to call each other by name. It's not just in schools & colleges, even in big organizations, it's necessary to wear ID cards which tell about your own identity. It Creates a More Secure Environment.
Identity cards are for keeping us safe. To avoid mismatching people, and to fight fraud, this is the best possible secure way to prove your identity.