It is called utility easement and they are correct. Utility easements do not give public the right to trespass. I worked telcom for 35 years our cables were in utilities easements and we could install or run anything required for our utilities. FYI, the public does not have the right to trespass on utility easements either and you can be arrested for trespass. The documented easement will show up when you do a title search.
Had several homeowners try to fight against our use of the easement and ALL, every single one lost in court. we had one who actually took a saw and cut our pipe in half which cut our fiber optics, it was carrying transcontinental fiber lines. It was originally installed for natural gas, but company I worked for were now using it for fiber optics, he wanted more money for the easement right, he was advised it doesn't work that way so he got mad dug up pipe and cut it.
When we responded to repair the cut he actually stood in drive way with a shotgun and would not let us on the property to repair the cut, demanding money for the right. Local sheriff who was friends with the homeowner would not get us access, saying it's his property, we went back with federal agents who informed the sheriff and farm owner they were violating the law.
To make a long story short the homeowner did not have enough insurance to cover the cost of the repairs which the homeowner was responsible for and he lost his farm. The bill was in multiple 7 figures, the fiber was carrying government lines, FAA lines between St Louis and Kansas City for airports, we also had contracts requiring us to pay many customers on our lines for down time over 5 minutes which he had to cover. Judge ruled he was responsible for all costs since he intentionally cut pipe then delayed the repair. Repair of fiber optics is very, very expensive.