Hi. Sorry but BS7671 is not statutory regulation and is not on legislation.gov as a statutory instrument. It is incorrectly called the regulations and should be referred to as BS7671.The IET Wiring Regulations are most definitely regulations. Whether or not they're as comprehensive as they could be, or as one might like them to be, is another issue.
Given the nature of your opening post, perhaps it is a lack of clarity where standards are concerned, rather than regulations?
All UK legislation has to be passed through Parliament and BS7671 certainly didn’t go anywhere near government.