Agreed. But what an audition tells me about the company is that everybody there was willing to put up with it. Anybody who has lots of options probably didn't end up there. So maybe the company is so awesome that good people were willing to jump through hoops to get hired there, but even so it's a pretty safe bet that they don't have the the best and brightest working for them.
You're assuming that everyone views try-out periods in the same negative light that you do. If that were the case, then your conclusion would be right. But not everyone shares your views. Some people prefer to have a try-out period, because it gives them a chance to evaluate the employer.
I'm assuming that the best and the brightest don't have time for a try-out period, because they're busy doing stuff, and don't need one because they can easily get another job.
A try-out can just be on the weekends. I'm sure some people can't even spare any weekends, but there are plenty that can. Many people work on open source in their free time - this isn't all that different.
And true, nobody needs a try-out period - but some want one, in order to help them evaluate their potential employer.
If your assertion is that none of the "best and brightest" want to test out their potential employer, then we'll have to agree to disagree.
