The type of meter socket shown is widely used throughout the MidWest, Upper MidWest States, in my experience. The PoCo usually puts a little wire and plastic non-reversible seal through the eye of the . . . well, hasp, or whatever the pivoting swing-down piece is called. This works to keep honest people out, you know, like door locks. If a service develops a history of problems (pirated power, non payment, etc.) , the PoCo bolts on massive proprietary locking boots that make the cover all but unremovable without their assistance.