It's not just communication cables. A couple years ago, the local natural gas utility came in and replaced all the underground gas lines in the development as 'preventative maintenance'.
It became pretty apparent as soon as they started digging up the street that the existing gas lines were not where they thought they were - often off by 10 meters or more. Needless to say, the local cul-de-sac was quite the mess by the time they finished digging.
At least we didn't find out about it the hard way - e.g. when some utility dig severed a gas line that they thought was 10 meters away...