I don't see that at all. The government is the authority behind real estate ownership, yet they have very limited responsibility toward existing owners if they make changes to, for example, zoning restrictions.
If, for instance, they wanted to flood your land for the greater good, they would have to buy it back at "market rate", see TVA. I know it goes against the SV mentality, but apparently these opinions aren't popular here so I'll restrain myself going forward.
Indeed. But if they made some zoning changes that resulted in a new part of town becoming a more popular place to live, they'd owe you nothing whatsoever.