When you place a ticket with 811 you are supposed to clearly describe the area of work. It is also appreciated if you mark out the area of work with white paint. Having said that, locators realize the difference between homeowners and contractors, and Dig Safe would much rather you call and not have the work area not clearly marked out, than not call at all.
Some utilities send a locator on every ticket, but most use their records to determine if a person needs to be dispatched or not (cost savings). If you say "I am drilling in the patio in my backyard" it is a possibility that the electric, gas, sewer, water, and communications companies will all look at their plats and say "we have no buried utilities in your backyard - you are good to go" without sending a locator tech. In some states, the utilities do this, in others the contract locator takes the brunt, in some the utilities send their own employees to do the locating, and in some areas the 811 contractor will provide the triage service to the utilities (for a low low fee of course).
The upshot of this is , you may or may not get a locate tech out there, and if so, they may or may not do you a solid by locating private utilities.
Oddly enough, this along with soils engineering is one of my past jobs. I used to manage the contractor that did mark outs for a large telecom company in NJ and was part of the NTDPC (National Telecommunications Damage Prevention Council) and CGA (Common Ground Alliance). It's been a few years, but not much has changed