There are plenty of commons that come with borders, the most trivial of which would be a patch of land used for grazing livestock.
Garrett Hardin himself has acknowledged that he made a mistake with the concept of "the tragedy of the commons". There is no such thing. Commons have all historically been carefully managed by a complex interlocking web of understandings, traditions, rules. The so-called tragedies correspond to (essentially in every case) powerful interests ignoring or overthrowing the management structures governing a commons to pursue their own self-interest.