Whenever you think of a military base you wonder why you need special stickers or passes to get on the base. Sometimes it is pretty obvious if you see the ships in the water or the airplanes on the run way as you are driving by on the highway. Other times if the base is located on a major road and you just see the gate or sign then you may wonder why you would need military stickers to park on base. The simple answer is it is for security and protection. For you and the staff that work at the military installation.
There are some military bases that you can drive on but to park you will need identification on your vehicle that you belong there. This way you do not become suspicious to security staff driving through the lots and on the compound. Base stickers also have expiration dates and when it is time to either get a new one or to renew one you need to provide your current inspection, proof of auto insurance and your staff badge. The gives them a way to show accountability for the vehicles on the military base plus who they are registered to in case one may be stolen or damaged. The auto insurance information is available if they catch you during a hit and run.
If you are not a staff member and are going to visit someone at a military hospital or on a military base then you will be required to get a visitors pass. This can be obtained at the main gate or an office if they direct you to one. The pass is good for one day and it allows you to take care of business but it also provides the government service with your information in case you are needed or there are inquiries made on you or if something happens and you become a person of interest.
The military works like most secured places and have policies to follow. You would find the same procedures most likely at a stock trading company or any place with high security. Except I do not believe they ask for a copy of your auto insurance information.