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.

This only lasts until dark patterns can be inserted that disrupt the ease of use that agents are currently providing. If I can't force the end user to watch unskippable ads or trick them into spending money on a service they don't need, what are we even doing?

The reason they don't have an API is that they want to upsell you on other stuff, and get paid to promote their partners.

There's going to be a huge fight over how that relates to AI assistants over the next few years.