Even if you use Bitcoins directly (for supermarket purchases, utility bills, buying gasoline.etc), it can be taxed. The government can just ask the retail chain to impose a surcharge on the Bitcoin payments. So if you are paying with BTC, there will be a 2% or 3% surcharge, and this amount will go to the government as tax.
Interesting point dude.
Some governments and countries recognize Bitcoin but they make a regulations that they will benefit it like inputting taxes from exchanges.
that's right they are panning to put taxes with exchange so they can benefits with btc, might be much better instead of banning bitcoin we should be happy if government will place some actions to make some earnings too like taxing local exchange in our respective countries in this way adoption or recognizing bitcoin will be much possible in every nations.