Watch an actual video of sewer inspection. Note the issues revealed: Partially collapsed/displaced sewer line and invading roots (several locations). Grease build-up is present, but not problematic.
What does this suggest to the owner? Replacing one section of collapsed pipe is a more urgent repair; de-rooting the sewer line on a regular basis is recommended. This would be a short-term, lower-budget approach. Potentially the combnation of cracked pipe replacement and annual rooting of the line may suffice. Ultimately, replacing the entire line will be necessary and may be the cheapest long-term solution. The sonar-detection unit will identify the exact location of the section in need of replacement which minimizes digging, disruption, and length of time to repair.
Without this video inspection, owners and repairmen do not understand the problem. Rooting now could actually worsen the problem by loosening the cracked pipe.