Microsoft, EA, Apple, Valve, Blizzard, Riot Games, all microtransaction-financed games, every iphone developer that sells their game instead of using advertisements for income, they're all developing software that make money off that initial software purchase.
I think his point is that developers provide the service of development to their employers. Employees at Microsoft, Apple, Valve, etc. don't really make a significant amount of their wage from sales, they make it for hours of work. In other words the argument is: "what is the difference between contracting for someone and working for them full time?" At the end of the day its just you providing a service for some period of time, compared to actually writing your own app and selling it on the App Store.
The subtle counterpoint would be in companies that hand out stock options,where there is a sort of indirect correlation between the sale of a unit and your wage.
Microsoft, EA, Apple, Valve, Blizzard, Riot Games, all microtransaction-financed games, every iphone developer that sells their game instead of using advertisements for income, they're all developing software that make money off that initial software purchase.