Baden Würtemberg doesn't give a damn about the complexity of the assessment, they already have to assess land value for estate taxes. The assessment argument is actually complete rubbish. The assessment rules for the rest of Germany are significantly more bureaucratic. Assessing building value is an even bigger nightmare because you cannot automate the majority of assessment work. You also don't have to asess every single building. You can asess the value of bigger plots of land spanning multiple properties and allow an appeal process for special circumstances.