Governments need taxes to run. Why not up the GST to 8% and nix income tax? The GST is newer, more universal and doesn't leak like a siv.
The discussion has taken place about implementing a national sales tax in the USA and the discussion initially included getting rid of the income tax - but now they want the national sales tax in addition to the income tax.
It is a rare critter who gets into government and doesn't end up wanting higher taxes.