Re: zero cost
The point is that calling 'free' a 'market' is misleading, at best it's an edge case, and that's straining to force it into the 'market' category.
'Free' doesn't float on the stock market, doesn't incur tax, and has no meaningful legal obligations attached to it.
'Free' is massively important to the world as an antidote and counter-culture the 'the market'. 'Free software' is indeed a tiny aspect of 'free', for most people 'free' is what people do to look after each other - there is no profit motive, no need or expectation of a reciprocal benefit.
The fact that some agents do make money off the back of 'free' (Mozilla) doesn't mean that 'free' belongs, of itself, to 'the market. The two can, and do, co-exist, but they are not the same.