Local Income Tax pain

Around 1 million people in Scotland live alone - and rightly in my opinion receive the 25% council tax discount designed to make the system fairer.  Under the SNP/LibDem plans for a local income tax that benefit would be scrapped - the average single person living in a Band D home in Currie or Colinton would lose around £400 a year.  Needless to say the SNP/LibDems have not been trumpeting this policy from the rooftops recently.  I wonder why ? Indeed the SNP even went to court to keep figures that had been produced by civil servants secret. What could they have to hide ?