1) Honestly, who doesn't? Everyone is biased. I am just telling you how I judge how people will integrate with my team. I have a rubric. Most people have some bias, e.g. 'no girls allowed', but try to hide it or are in denial.
2) but there actually is not enough information to appropriately judge
There never is. I can only look at resumes, references, and any public postings. How well a person *really* performs is only shown over a matter of time. But there have been time when I was not as critical as I should have been and it blew up in my face. My gut said 'no' but my brain rationalized things. I then spent 90% of my time dealing with a troublesome employee or team member. By the way it cuts both ways. I use the same method when interviewing employers.
3) The guilty verdict would come down, before the defendant even got to made their case repudiating all the apparent "evidence" from the prosecution.
If you want to find out what a person is really like observe them in unguarded moments. Not the front they put up. That is how you screen out sociopaths.