If you need support, you can buy it from Red Hat, Oracle, Canonical and thousands of other vendors. This is probably better than the support you'd get from closed source vendors, because you can both see the product you're using in it's entirety, i.e. no man behind the curtain.
So the process is more transparent and thus valuable to the consumer.
Sure you can buy support. That's why Linux is the industry standard....oh maybe not. One needs to ask why that is. You did hit the nail on the head though in one respect, show me a big company, especially a government, that wants transparency of their system. Any knowledgeable Linux hobbyist on the street will have a copy of your basic (or more) code (not that some can't get their hands on MS code, I've just seen many more putter with the various Linux flavors). I'm not knocking any of the multitude of flavors of open source Linux, or the pay for versions of Linux and Unix available, I am of the opinion there are some very good ones. The difference between an single MS and a Linux administrator in these parts is about 25K+ a year, and thats just for servers, their client PC's still run Windows. Now imagine how many an entire govt. entity (like Indonesia) would require.
I can't comment on the paid support or its cost, since I've never personally used it, but if you have a truly open-source system (servers and clients) that fewer people are trained to operate or work on it, the bigger the $$$upport dollars are and maybe even regular employees that may never have seen let alone used it before. There is a reason why companies like Oracle and Sun MicroSystems, make big (maybe not MS big) dollars while have a (much) smaller piece of the pie compared to MS. Choice is great though.