They will need to hire (or continue to hire) local specialists to install and maintain the software though. I would not be surprised if the wage cost is higher than the cost of the software.
But those money remain in the country and make its economy feel better. Increase consumer spendings and yada yada.
Money that you ship off (even after tax) make it worse.
If the commercial software needs as much specialists to support, what's the point anyway? The whole idea of commercial software is outsourcing work instead of doing everything in-house.
Well, it depends on the software. If we're talking about Windows and Office, they're very high quality, standard pieces of software that are an excellent choice for the educational market. As well as having a larger number of people already experienced in using them, both as users and specialists.
For example, it's worth paying for Windows Server just for how much easier it is to run large deployments of PCs and users from it using Active Directory, group policies and suchlike. Rather than hacking something up in Linux or whatever.
Your argument assumes that the commercial and open-source offerings are equal in quality and features, when in fact the major commercial software is far superior.
My argument isn't an abstract commercial vs open-source one: it all hinges on the quality of the software: if Microsoft suddenly open-sourced their entire operating system and productivity suites, they would still be the top choice in my book.
You can employ mixed approach.
For example, buy Windows while using OpenOffice.org.
But I argue that for large-scale development it is feasible to develop a Linux distribution that will fit schools better than Windows ever does. With everything school workplace needs, installable in one click.