Open source as kosmos
Basic economics tells us that lacking government coercion any good supplied by the market must have continual price decreases as competition drives suppliers to find less costly means of production. There is nothing in economics that says this function must be a smooth and gradual curve. In fact, if a market is a chaotic system (it is) then a discontinous curve may be a better fit. Historically, the first operating systems were tens to hundreds of thousands of dollars per machine during the mainframe days. In the 70's several smaller computers (mini-computers) became available and OS prices dropped to the thousands of dollars. In the 80's Bill Gates started producing an operating system that cost in the high tens and low hundreds of dollars. Now, Linux costs zero dollars for a license. So a rough fit might be a curve that is flat for a number of years, then drops an order of magnitude or two, and repeats. Linux is the latest drop and that is to zero
Perhaps the reason that Linux may not be as 'robust' as Windows right now is that the price for 'robust' software has not dropped as fast as the 'basics' of Linux, but might do so with time?
Eric Raymond in The Cathedral and the Bazaar suggests that the way Linux is developed represents a fundamental shift in how software is developed. This shift should not be surprising to free-market economists. The traditional (Cathedral) style of development correlates well with command-economics, i.e. a central authority directs each person's actions, with each person having little to no autonomy. In the open-source (Bazaar) model each person has full autonomy and each bit he does is evaluated by the market and accepted or rejected. In open-source development each developer competes at the level of code snippets, whereas a traditional developer has no (direct) competition to measure against. To an economist the Open-source model is the more efficient method in the same way that free markets are more efficient than command economies. From this we can see why the price is driven down to zero, and we should expect that over time the open-source model should produce better results.
It seems like the Cathedral/Bazaar dichotomy is essentially the taxis/kosmos dichotomy, and that Windows, being propietary sofware is designed from the top-down whereas Linux, being open-source is evolved from the bottom-up. Interesting, I never thought of it that way.