Why am I opposed to government? I suppose it comes down to the radical idea that certain moral that all people, even in government, should follow. It is wrong to take property that is not your own. It is wrong to kill a person who does not pose a threat to others. It is wrong to threaten aggression against anyone who tries to compete against you.
Some might say that tax, as opposed to being taking someone else's property, is payment for services. But what if we do not want the service the government provides. Often times the government threatens aggression against those who would try to compete against it and other times you can hire competitive services, but you still have to pay for the government services too. Only a government can enjoy that luxury.