Just as an aside, there is another reason to design and build to class. Long term value. Besides lowering your insurance premium or being a requirement for commercial use, having a vessel "in class" (built under survey and up to date inspected) means it's a considerably more secure investment.
While it's rare to build in class in the US (yes, production builders talk about ABYC and today ISO for export reasons), it's quite common to build to class in Europe, especially among higher-end semi-production builders. This is just a further assurance to the buyer that his investment is good. A third party has checked all calculations, materials, and practices, and added their expertise to the final outcome. Boats routinely fetch higher prices in Europe.