Orals have a lot of advantages, but they also make it very easy for unconscious bias to come into play, in that all the criteria for grading are soft.

Good point, this is also one of the aspects of skill. There are techniques you can use effectively to mitigate this.

One unfortunate thing is that poorly done, orals can be very uneven.

There already is unconscious bias. You can see the student's name, their penmanship, their writing style, you likely know who they are, etc. An oral exam just changes things by changing the bias to accent, inflection, annunciation, skin tone, dress, etc.

When I was in school, 95% of grading was blind and nothing outside of exams was handwritten.

And while it was possible to de-anonymise, the academics were all in support of blind grading so why would they?

The only exceptions were projects where everyone was assigned a different topic, and graded presentations.

Of course, this is simpler in STEM subjects - it's not like you can guess someone's race or gender from their switching power supply design. Subjects that prize in-class participation and lengthy essays would probably be harder to blind-grade effectively.

This also depends quite a bit on class size. If you are one of 9 profs and 36 TA's on a whole year of a 1st year intro course, you can get together and batch mark finals very effectively blind.

If you are teaching a 4th yr/masters mixed class of 11 by yourself, you pretty much get to know who is who whether you want to or not. I suppose avoiding handwriting can help if it's appropriate (e.g., won't work on a math course) but I suspect you'll know everyones style by then anyway.

The examiner doesn't even have to use the oral exam to give a grade. They could use that part simply to figure out whether the student passes or fails. It's very difficult to cheat in an oral exam. Combine the oral exam with the written exam and you could get an overview of what the student knows.

This privileges confident speakers. (The same way written tests privilege confident readers, and standardized written tests privilege those who have the time and resources to study the standard.)

I'm not sure about that.

It certainly could, but it also certainly couldn't. I imagine being confidently incorrect is likely to produce a worse result than being unconfidently(?) incorrect, for example.

Similarly, a less confident speaker may end up spending more effort justifying their answers, which could better expose their knowledge.

I think it would depend quite a bit on the examiner in this case. Some people may even be simply biased against particularly confident speakers, particularly considering the relative positions of the speaker and examiner.

It doesn't if the examiner understands the material. You can't bullshit someone who knows much more about a topic than you do - bullshitting with confidence will only make you sound like a fool.

If the examiner isn't much more knowledgeable about a topic than their students, then something else has gone wrong.

But you can appear to know less than you actually do through a lack of confidence.

Right, but that's why it takes a bit skill on the part of the examiner - you need to be able to support people through their nerves and lack of confidence.

Not much if you do it well. Confident and wrong won’t get you far, either ...

The real world also privileges confident speakers.

Schools should be teaching kids to be confident speakers and readers from an early age.

If teaching worked 100% we wouldn't need exams.