The purported reason is because the survey was designed by a private company who claims the survey to be their intellectual property. Similarly, if a school screened a controversial film, a parent could not ask the school for a copy of said film, because the school doesn't own the intellectual rights to it.
This is a microcosm of what happens when public institutions, whose records and dealings are considered to be part of the public record, uses private contractors. Other public instituions have used this to deny access to what is usually a citizen's right to know: e.g. public worker salaries being maintained by a private payroll company.
It was not the text of some laws. It was engineering standards incorporated into certain building codes. The laws were like: "buildings shall follow ASME x.y.z" (to use a software analogy, it would be like requiring something to conform to POSIX, a standard the text of which is not freely published).
Regarding the "text of some laws", there was actually a story on HN about the city of the District of Columbia asserting copyright to their laws and making it only available via a private company:
Is this distinction interesting in some way I'm missing? If the engineering standards are mandated by law, they are effectively law themselves, so I would assert that "the text of some laws was restricted by copyright" holds. Referring to external standards was the mechanism in the cases I was thinking of, to be sure.
This is a microcosm of what happens when public institutions, whose records and dealings are considered to be part of the public record, uses private contractors. Other public instituions have used this to deny access to what is usually a citizen's right to know: e.g. public worker salaries being maintained by a private payroll company.