Those payments were not taxes, they were extortion payoffs to ensure the safety of the American Navy at the time. The United States was still a new nation, and as such had to keep diplomatic issues to a minimum. As soon as Khilafah was abolished, the entire issue disappeared. The payments were also not to the Ottoman Empire. They were to the Barbary States, more specifically to the pirates of the area, as proven by the lack of the Sultan's signature.