This is a fair point. In honesty I think the intention behind building codes is to prevent builders from building buildings that endanger others (e.g., fire hazard) or selling buildings where the buyer is not aware of the risks. The former I think we can all agree is necessary and fairly straightforward. I think the latter is more complicated. Perhaps people can't effectively judge the risk they take on by living in a potentially less safe environment and so are not willing to pay for improvements that would improve their utility?