Sewer problems here are relatively uncommon, and when they happen they are usually about ground movement rather than old pipe.
Modern pipe, different failures
Kiawah was developed comparatively recently, so laterals are modern PVC with sealed joints. The classic causes elsewhere — roots in clay joints, corroding cast iron — largely do not apply. What does happen is settlement, where ground shifts under a section and it sags and holds water.
Sand and made ground
Much of the island is sand, and sand moves. A lateral running through it can develop a low spot over the years, which is by far the most common sewer finding we see here. That is a repair to one section rather than a whole line.
Camera first, always
Because the pipe is generally sound, footage usually shows exactly one identifiable problem in one place — which means a targeted repair rather than an expensive replacement.
If major work has been proposed
On a house this age, that is worth questioning. Ask what was found and ask to see it.