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.