I would rather work for free than have half my face illuminated.

That's interesting! Purely speculation, but I'm wondering if you're more likely to work for free (or get asked to) if there is going to be less ongoing hassle afterwards – hence taking photographs / playing music for free is going to be less onwardly demanding of anyone's engagement than say, being a backend developer, which might involve you tweaking stuff for an amount of time afterwards.

It also means the person who provides a service has a bit of power thanks to being locked into a relationship where onward work/costs might be involved. So perhaps people are more likely to ask somebody to work for free if they think of it as a single event which doesn't involve them being held to ransom in some way, down the line.

Of course, from the point of view of the person providing the service, their work lives on. So anybody providing a service is going to think more than once about doing something for nothing, when the results are still going to be around, and long after people have forgotten that you did it as a favour. Probably like everybody else, for that reason if I do something for nothing, I still have to do it to a high standard. I can't just do a sloppy job because I'm not being paid. It's a true test of whether you feel passionate enough to want to do the work!