I disagree. There's no reason that properly educated and briefed volunteers can't do a lot of the same work. Just look at citizen scientists. [0] There have been studies that have shown them to be just as effective as experts. [1]

[0]: https://en.wikipedia.org/wiki/Citizen_science

[1]: http://journals.plos.org/plosone/article?id=10.1371/journal....