Regarding underground electricity wires... Just saw a report from Miami where a neighborhood lost power because the roots from the toppled trees ripped up the underground wires there. So while it would help in many (most?) situations, it isn't foolproof.
And EACH outage of that type would be more expensive and time consuming to fix.
Airborne/strung wires are VERY EASY to 'see' where the problems are; buried wires are NOT easy to 'see' and require special electrical "bridge" meters & equipment to "guess" where problems (shorts, opens, cross-connections) are located underground.
The telephone companies have always had very sensitive test equipment for locating almost all line and cable faults. From inside the central offices (CO's), local test desks (LTD's), remote TD's, and of course devices used by outside plant crews.
A full set of line tests are run on every originating and terminating telephone call for most possible line faults, completely transparent to the caller/callee. Mobile calls too, but far different types of tests.
Certain 'hard' faults will result in not completing the call, but other, more minor faults will just result in an internal report, and may or may not be noticed by the customer.
The CO's have both various manual test panels, and automated ones (ALIT). Old style bridge test circuits and newer forms of TDR's are used.
Even as the switches have almost all become digital, such devices are still needed for copper cables inside or out (whether telco or cable company). A different suite of similar tools are used for fiber optic and co-ax of course, but many of the same principles are used.
Many different types of TDR (time domain reflectometer) are used (have one in my workshop). They are even used with microwave waveguide.
https://en.wikipedia.org/wiki/Time-domain_reflectometerThe power companies also use similar equipment to locate faults.
They all can work on active cable and lines.
Of course, like all tech stuff, success depends on the skill of those using it.
The equipment will locate the fault, and it's distance, pretty accurately, but some factors can throw that off a little. No "guessing" involved, if there is a question before digging, some other test equipment can pinpoint the location.