It's about pure logic, hedging bets and pattern recognition.
There are simply too many people to judge each one on an individual basis. In fact, there are more people on this earth than their are seconds in your life, even if you were to live twice as long as the oldest person in the world. You could walk through a city and pass more people than you'd ever truly know in your entire life.
When all you know are the basics, you have to rely on them to make your decision. When all you know are gender, race, age, those factors are the ones you should go on.
So, you should judge each individual as an individual SHOULD that be an option. But that doesn't mean you should discount prejudice, as it is a manifestation of common sense. Pattern recognition, the basis for human intelligence, and basic odds leave us with the ugly truth that stereotyping is simply a logical move.
Saying ALL black people are bad, that's stupid. But if you have to make a choice, between people you don't know, you should hedge your bets and go with the option with statistical greater return, eg, hire the Asian over the Black on a racial basis, simply because evidence points out that that will give you a greater return. As long as your prejudice can be backed up by evidence, which, as Sup Forums can show, it can, there's no reason not to act on it except psuedo-religious dogma from the cult of multiculturalism.
As long as your assumptions are based Investors do not operate on absolutes, they operate on speculating on the best returns. They might make a bad bet sometimes, the 10/1 shot with a 5/1 payout might come in over the 3/1 shot with the 20/1 payout, but that doesn't mean it was a smart move to bet on the former over the latter. And you always go with the better odds. Is it fair? No. Is it logical. Yes.
So understand that it's just not fair. Life isn't fair.