Educating of clients to the reality of geotechnical / foundation engineering is an ongoing time consuming issue. Many of our clients are non engineers, often professional, well educated people. But they are often unaware of the basic principals. There expectations may exceed the engineering expected performance of the foundations.
Clay soils are about like sponges that have very sensitive pressure displacement curves that change with changes in moisture content, pressure, and time. Any foundation placed on soils will move in a response to pressure, and changes in pressure, as well as time and changers in moisture. Place two similar footings on similar soils, the one with a greater load will move more. Place an identical footing with similar loads on different soils, and we can expect different movements. Place two similar footings with similar load at different elevations within a site, we can expect different movements.
The differential movement between different unconnected foundations is the part that causes issues. Perimeter strip footings are usually tied together with a foundation wall, and some reinforcement. But was it enough and put in correctly? The interior footings are expected to move differently, and adjustable columns are now required so that the main floor can be maintained in a straight line. Adjustment must be maintained, and the structure must be build such that adjustment can be made.
Note that engineered fill is not addressed in any useful way in the building code. The building code, part 9, was developed for traditional housing, and many of the new bigger house exceed traditional; hence, the building code prescriptive portion may not be adequate to address all the issues. But the building code has an escape clause, something like; "if the code is not adequate, consider engineering the project as per the remainder of the code". How useful is that?
There are standards, but first is the standard suitable? Secondly, was the standard followed? Following an unsuitable standard will lead to problems.