There are a lot of presuppositions in your statement. It doesn't provide an answer to "Should we tax" from first principles, but is just the current situation in a world dominated by oppressive governments.
Right because the answer to that is even more obvious but I'll spell it out anyway.
The reason we should tax is that not taxing would be far worse. Point me to one of these mythical non-"oppressive" governments at any point in history that didn't tax and wasn't awful.
