What about enforcement? Does informality result from non-enforcement?

Not always, but there are examples. For instance, with regards to the titling or privatization of informal housing and settlements, governments sometimes opt not to enforce, although legally prohibiting such arrangements. As a result, the level of conflict is low. This is a typical example of an “empty institution”, because “[p]articularly when sensitive issues are at the center stage of social and political debate, ‘empty’ institutions tend to surface as a sort of institutional compromise. In these situations, institutions can become detached or ‘decoupled’ from social actors’ behavior to avoid conflict. As such, the empty institution is, by and large, ineffective and ignored, yet simultaneously socially accepted, little contested and, in effect, to a certain degree credible.” See P. Ho, “Empty institutions, non-credibility and pastoralism: China’s grazing ban, mining and ethnicity”, Journal of Peasant Studies, 2016, 43/6, p. 1147.