Bedrock decides the price, and the trench is the only place it shows
Shallow limestone turns a sewer or water service dig into rock excavation, and nothing else you can film explains an estimate that fast.
Most people here have heard that you hit rock. Almost nobody has watched what that means. A trench that stops dead on a solid ledge, a machine changing teeth, a day of work that moved a few feet: that is the entire argument for a number the homeowner was ready to fight about.
Put two digs side by side. Soft ground in one clip and limestone in the next, same depth, same length, different week. The comparison makes the point without you claiming anything.
Shoot the depth with something in frame for scale. A shovel handle, a section of pipe, a technician standing in the cut. Rock reads flat on a phone screen unless a viewer has something to measure it against.
Rock sets the clock as well as the price. A dig that takes an afternoon in Rutherford County bottomland can take days on a Sylvan Park lot, and a homeowner who watched the ledge stops asking why the crew is still there on Thursday.