Unlocking one to unlock the whole thing is the point. The fenced in area is someplace they need to keep secured from the general public but that multiple companies or agencies need to access. By doing it this way any authorized group can get in but is responsible for their own key. Usually they look something like this. Unlocking any one lock will open the whole thing.
The "convoluted" solutions to this are actually the best ones.
Searching for it... Texas Bow Hunter has a thread about these locks.
long and circle are two of the neat approaches.
These are known as "shared access locks" - https://www.amazon.com/Gate-Keeper-padlock-multi-access-shared/dp/B01AMQZKV0 is another design. And once you know what to search for, you can find some rather complex ones - https://www.everlocksystems.com for example.