They don't make any sense to me. So if you pay a "head tax" (non-muslim) you're ok? But in the next breath if you don't convert you die? They need to make up their minds.
They've always done it that way. Usually they kill enough non-Muslims to make their point and then when the rest have surrendered, they collect the tax from and enslave them. This is because Muslims are incapable of running an economy and producing anything, so if they kill off all the productive Christians and Jews, they know they will cut off the money supply.
They have done this consistently in taking over new areas - first they kill, then they enslave.