My guess is that UK laws are written in a convoluted manner in an attempt to cover every possibility that the drafters want the law to cover.
US laws, on the other hand, are written in a convoluted manner to disguise the fact that the drafters really haven't any idea what they're trying to control, and often aren't sure if they want to require some behavior, or prevent it. Our Tax Code is particularly confusing, as that is written with the intention of keeping up the pretense that it is a "voluntary" system, and to hide the fact that the Code isn't actually the Law, but merely instructions to the IRS telling them what the legislature wants them to do in the Regulations, which may or may not be the same thing, and isn't always what the IRS decides to do anyway.
