There are always ways and means to avoid paying taxes, especially if we are talking about cash transactions and P2P deals. We all decide if we want to pay those taxes or not. If you leave digital fingerprints for monetary transactions, you could get caught and questioned. If you don't, the chances are significantly smaller.

I think we should stop dreaming about a Bitcoin society that replaces all traditional institutions and instruments of power we have today. Let's just hope Bitcoin's development goes nicely and in the interest of its holders. It's an economy that works independently. A sidechain to traditional finance if you want. I am not dreaming of a world where the governments won't tax people at all because they are using Bitcoin only. All countries need those revenues and rely on it. Chaos would ensue otherwise. A world-wide mining ban is a more likely scenario (although highly unlikely itself) than the governments giving up on taxing their citizens.