For the umpteenth time, I do not willingly pay tax. I pay tax because I don't want to:

a) Go to prison;
b) Leave my friends and family;
c) Live off the work of others.

You can call those 'choices' if you want - same way as if you were mugged at knifepoint in the street, you might 'choose' to give up your wallet to avoid being stabbed. Doesn't make it voluntary, does it?