I always insist on fiber optic between buildings, for the data connections.
But there has for a long time been issues with shared metallic paths between buildings with separate services (e.g. a neighborhood of homes on the same metal water pipe, cable TV coax, etc). If one of them loses neutral on the service drop, guess what gets to carry the difference (and all along it was carrying a fraction of it, anyway). I'd rather my water and gas come in on plastic piping, and the phone/TV/internet come in by fiber or RF, just to avoid those issues. Eventually, I'll get it arranged that way (it was hard enough just getting the cable company to properly ground their stuff).
Here's a fun one to consider:
Utility service drop comes to the house. A whole house (25kVA or more) generator is inside the separate detached (and powered) garage. How can you wire up so the house is powered by the generator, and not only comply with 250.32(B)(1) but also be sure the proper transfer(s) exists.
