Cause the goverment is telling us to do so, if we don't agree with that law we could have problems with doing anything in country that we live, that is why we want to pay them.
That is right, we don't have a choice that is why we are choosing to pay for taxes even though we don't want to lessen our money, but at some point it is fine since it is for the benefit of our country for the poor people to have the chance to live by providing them by the government those basic needs and for us to have a develop country.
It's not a free agreement for paying tax or not. People have to pay the tax, they don't have option like not paying it. It's a force applied by the countries rulers. This ruler can be a king, democratic governments.