Sure, the software has a bug. Software does. Almost always. What is broken here is that it is possible to get stuck in an airport with no possibility of escalating sensibly to a chain of human beings with agency to resolve it. You could have a software process which works 99.9% of the time, and have staff at hand which could solve any solvable remaining issues like this one. They call the Home Office internal hotline, explain the issue, resolve it by manually interfering on the spot (and have a bug filed), and everyone carries on.
Instead, we demand a 100% correct system, and save money on actually having people around who can deal with the edge cases and make sure everyone has a good time. Of course, getting a project from 99.9% to 100% costs a lot of money, because that includes literally all edge cases ever (getting to 100% is as likely as reaching ∞ by multiplying any given starting number by 2 until you reach it), and so it will likely end up being more expensive in budget overruns than the 99.9% plus humans system.
Obviously, politicians must choose for the fictional 100% case, because they can't afford the cheaper 99.9% plus human one.