There is a method to how these things are covered up. Whoever is causing the digging has the actual work done by a contractor. Unless the contractor can be proved to be directly supervised, this gets the instigator off the hook. Then they call in "Miss Utility", another party. If they didn't clearly mark the line, they may be the party at fault, but repairs will destroy the markings.
I was burned out of a townhouse in Northern Virginia a number of years ago by a cable company crew drilling into the underground power lines. Everybody pointed fingers at everybody else. My insurance sued, but it took years to come up for trial, at which point the cable company settled, and I never got my deductible back.
Verizon lost maybe 50 yards of buried cable, and the power company at least as much. They both seemed to take the attitude that they caused about as much damage as they suffered, so it was a wash. As long as it is only the consumers who really suffer, I doubt any of them much care.
[TELECOM Digest Editor's Note: That damnable mess here went on for several hours. We officially got back on line at 9:55 PM, or about 12 hours after it started. They had hoped to have the repairs finished before it got dark outside (which would have been about 7 PM this time of year.) It turned out they had to take bright lights and set them up there in that field where the contractor had been working. What a mess it was! PAT]