As much as NDA involving public officials is problematic, there can be legitimate grounds for having them, for limited time frames.
When a company is looking to locate to an area, they need to line up land and resources. If everyone knows that company Z is looking to acquire land, speculators may jump in and artificially drive up prices. There can be a few other reasons as well.
Hiding info from the public because the plan is to stick the public with the costs is bad. Look into the shady AF tax diversions. Cabelaâ(TM)s negotiates sweetheart deals where the sales tax collected stays with them. Some large companies get deals to keep their employeeâ(TM)s state income tax withholdings.
None of that should ever be kept from the public and should be required to be publicly posted