There's currently quite a bit of discussion flying around regarding whether GitHub should be used in place of a resume when considering candidates for a software position. Part of this discussion led to some calling open source software 'unpaid labor.'
I think that the discussion has been taken in a bad direction because the connection between a person's contributions to OSS and 'unpaid labor' is indirect. It requires a qualifier - a subjective analysis of the contributions, before the connection can be made.
For some luck folks, contributing to and building open source software is a full time job, for which they get paid. For these people, building their "resume" on GitHub is a full-time, paid process. For others, contributing to OSS is a hobby - they enjoy it and invest time into it.
For some people, however, overcoming obstacles to contributing to OSS is very difficult, and really becomes work. It's easy to get held up by these obstacles, even if you're passionate about software. Some people get fully passionate and invested into software at their company, which unfortunately ends up being proprietary. Does spending 1000+ hours on a project at work mean I'm not passionate, or don't have a good portfolio? Yes, it does - if you consider GitHub as the person's portfolio. This is wrong.
So if one assumes that in order to be seriously considered for a position, she must have a strong GitHub portfolio (which isn't a big assumption, considering a huge number of companies now request you provide your GitHub profile when applying), then this means that, outside of her job (about which I might be very passionate), significant other, kids, exercise, and hobbies, she now needs to invest a significant amount of time contributing to software on GitHub - just to be considered. This is unpaid labor.
This is an example of someone who is not just comprising a list of previous projects, or detailing her accomplishments, but actually doing more work, outside of work, not because she's interested in contributing, or intrigued by a project, or doing it for a hobby, but because she is required to by a new system of judgement.
Open source software is not unpaid labor (nor is contributing to it), in-and-of itself. However, requiring that someone work for long hours, over a long period of time (because no one makes meaningful, invested contributions in a short time), for no money, just to be considered for a job, is unpaid labor.
The whole situation sucks because someone who has a weak GitHub "portfolio" must immediately be on the defensive for the reasons why. Looking at someones contributions to OSS seems great - but so does hiring based on extroversion. Someone who immediately seems outgoing and lively might seem like the better candidate, but an introvert could be more qualified and a better fit for the position, despite coming off as shy in a first impression.