The particularly infuriating thing about this, is that even with the first half of the steps screwed up, if you get your shit together, and put every damn person and dollar you can behind the job, you can still finish the rest of it and get everyone and everything out, or close enough to it, that you can still call the evacuation a success.
The thing is, at no stage at all did the Biden presidency or the Pentagon display any meaningful level of competence on this. They started cooperating with the Taliban and gave them lists of collaborators, while hiding behind the fences at the Baghdad airport.
Meanwhile, the British were sending expeditions of their own soldiers out past the perimeter to collect their citizens and local support staff. Which proves that it was absolutely possible to do so.