Keyfob is solving the wrong problem, It's not an authorization problem. This is a tragedy of the commons (ToC) problem. The tragedy of the commons arises from the situation in which multiple individuals, acting independently and rationally consulting their own self-interest, will ultimately destroy a shared limited resource, even when it is clear that it is not in anyone's long-term interest for this to happen.
The solution is, sadly, government. Someone must act as a guardian for the commons, to protect the resource for the betterment of all.