Tax valuations and "zestimates"

The tax valuation and true market value unfortunately are all to often to completely different from each other.  They are all over the board for most properties out there and the science behind a tax valuation is completely broken.... Long story short the tax value is not a good metric.... and the "zestimates" on zillow are heavily influenced by the tax valuations further complicating the general  public perception of real estate values.