[cooper12]

In a more general sense this can be applied to any form of crowdsourcing. How can open source software work with a bunch of strangers adding code? How can citizen scientists provide accurate data? How can airbnb provide a good hospitality service? How can uber be safe and on time?

It's all just our natural prejudice towards people who aren't "qualified" or experienced. Humans are pretty terrible at judging qualification. Either they'll use some irrational subconscious criteria like the person dressing appropriately or appearing confident, or they'll rely on faulty measurements like scores on some test or having some sort of certification. Sure these are all useful to some extent but we have to start realizing that design has a limit, especially when you enter fields governed by things other than hard science.