Oh. Drop the passenger of at an appropriate interim location, and you're forced to fund part or all of their subsequent trip accommodations to their original destination.

And suddenly we are back to the human help desk again.

Who is going to decide what is reasonable cost for covering the replacement trip. Is a bus ticket ok? cab ride? limo? Should the cost of time be counted for?

Reasonable cost is something you would define through policy, and would likely be based on percentage of trip traveled, initial cost, and some percentage as a premium. Even in human staffed companies this isn't left entirely to the discretion of the person handling the case.

I 's not entirely simole, but let's not act like it's impossible either. People use Google apps and services with shitty support all the time, because Google is fairly good at reducing the times you need support and also because they are pretty good at saying "you pay $X, we provide Y, and Z is what you can expect if there's a problem, and if you don't like that, go find a competitor."

Make breaking the contract painful on both parties, and hopefully it will be rare. In the case where it happens, you try to make sure the normal penalty covers it, and where it doesn't you eat the cost and look at why it failed and fix it if you can.