If hotels, or google, or travel websites wanted people to book programmatically they would have an api.Remember when Google search had an api? In the end the human is responsible for the purchase. I think when the dust settles, AI will offer a "do you want to purchase?" and then the human will press the button. Or ChatGPT or somebody controlling the last step will have that button, and services will accept it (like Instagram) because it brings business.