Fine.....just call it an internship
When my wife was going through her Master's program she had to do an internship. Here's the kicker...she had to PAY THEM so she could "work" and get her hours. I think a brewery could do the same. How many inspring homebrewers would love a chance to "work" at a professional brewery?
OK, that's the legal answer. So it sounds like if I help my neighbor set up for a garage sale, he has to pay me. The key word here is volunteer. No one is REQUIRED to charge for their services.
That's not correct. The onus to pay for labor is on the employer, not the employee. The employer must pay for the services, unless it falls into one of very limited exceptions to the FLSA. Calling one a volunteer or intern does not avoid liability under FLSA for an unpaid employee. Both a volunteer and intern carry specific requirements to provide uncompensated labor.
In the case of an unpaid internship, it must be part of an academic program for academic credit in which the work performed is primarily of an educational value and related to the academic program, not offsetting the work otherwise performed by an employee. So, for example, a brewery could likely take on an unpaid intern who is receiving college credit in a brewing program as an assistant brewer but not as a keg washer or some other entry level position in the brewery.
In the garage sale example it turns on the several factors but most notably one can volunteer for a for-profit venture if the work is not of the kind the venture operator would otherwise pay somebody for. So for example if your neighbor's garage sale is so large without your help he would have to hire help then he would probably have to pay you for your help. If you are gratuitously helping him but he would have been able to do the work on his own, then probably not.
A more related example would be somebody who decides he wants to tell the world how great brewery XYZ is. He tells the brewery he is going to blog every day about the beer and they tell him to have fun and thanks. He blogs away on his own accord. He is volunteering his labor (blogging) to the brewery because the brewery otherwise would not pay for some guy to sit and blog on his personal blog about the beer. However, if they had him blogging on the brewery's website, it's probably employment and no longer volunteering because if the brewery wanted a blogger they would otherwise have to hire somebody to do it or use internal staff (which is already paid or the owner).