You are wrong, people care. Maybe most end users do not care but Azure is not marketed to end users. It will be marketed to businesses and they care very much about which technology they stake their entire existence on.
And no you do not have to compile from source or even look at the source to get the benefit of open source. The main benefit of open source from a business point of view is that other people can look at the source. Thus, if the technology you are using is popular you can be sure that there will be multiple companies that will offer support. Thus, you are not dependent on the whims of a single company. You can always use the power of the free market to ensure that you get all support and services at fair prices.
Furthermore, if the people that provide the software or the cloud service decide to go away or raise their prices, if you use open source, then you can be reasonably sure that someone else will pick up the slack and offer the same software and/or service (again as long as it is popular enough).