Why not just cut GST for everybody? Instead of taxing Uber more, tax taxis less. Drivers and Uber still pay income taxes, fuel taxes, relevant tolls right? If they want to simplify taxes -- as they claim, the best way to simplify is simply to eliminate.

Lower fares mean more revenue for drivers and Uber and thus more income taxes collected. Removing taxes from goods, means lower prices which means you sell more and then generate more tax revenue. Laffer Curve 101.