My personal area of study falls into Russian History. However, having just finished reading The Comanches: Lords of the South Plains by Ernest Wallace and E. Adamson Hoebel, along with The Comanche Empire by Pekka Hämäläinen and Empire of the Summer Moon: Quanah Parker and the Rise and Fall of the Comanches by S. C. Gwynne, I would comment that neither of these three books speak of the Comanche having any kind of unified, centralized form of government in the Comancheria/Llano Estacado. These studied described the Comanche as having an extraordinary loose tribal band system, with really no one individual or individuals in charge. What we would think of as "chiefs" were leaders only in so much as people agreed to follow them. So in your example, one band could levy a tax and give safe passage to a group, but from these sources, no other band would be bound to honor that decision. As for exacting tax and allowing white settler movement, all three of those sources state that the Comanche were hostile to white settlers and generally other tribes, (except for the Kiowa). The Comanche exterminated several smaller tribes and drove the Tonkawa and Lipian Apache, as well as other tribes, completely out of the rich buffalo hunting grounds of the Comancheria. The Comanche are also supposed to have stopped Spanish expansion north from Mexico and by the end of the US Civil War were actually rolling back white settlement through raiding. So, these three sources contradict what your textbook states or suggests.