Why this is better than central DB: Allows govt to outsource IT Public interest in the data will result in 3rd party clients being developed It makes that govt data more accesible for all parties - no gatekeeping
Use case examples All modern houses have a ton of compliance docs - window installers, insulation installers, HVAC, etc. Recording that data on the public blockchain provides a universal storage mechanism and API to that data. There is no reason for that data to be private / behind gatekeepers and a whole range of stakeholders - home builders, academics, environmentalist - want access.
Tracking highway per mile marker. Similar to the home building example - the govt collects a whole bunch of data (accidents, pollution run off and constituents, expenses). Many entities could use that data and relying on all govts worldwide to provide it seems cumbersome to unlikely.