Government uses contractors for lots of reasons -- many of which are more about shifting risk/accountability.
Operating in a unionized environment is challenging because of the inability to fire, but that's more a leadership issue than a cost issue. For most of the infrastructure services we built, during the growth phase, we'd be 25% FTE cost (including benefits), 25% contractor cost, and 50% hardware and software, with the mix depending on the service. Software projects had more contractor cost, and some specific, high skill infrastructure areas had more contractor cost.
The key to a sustainable service is distinguishing build/grow from operate. When the service is in a operate/steady state phase, the government employee staff should be running it 100%, and bringing in SME contractors as needed. That's how you operate effectively.
As you do this stuff, you build a cadre of smart employees who develop the ability to build more and be flexible. You never run out of projects. By owning the services and processes, you save money unless you're totally inept.
All three of them are using Cloud Foundry as their platform. By way of disclaimer, I work for Pivotal, which is the leading donor of engineering to Cloud Foundry.
Do you have some more information on this? To my uneducated eye, it looks like GS14 (with benefits) is substantially less than a good software dev would make in the private sector. I would be very interested in a government job if I am incorrect.
Granted the salary at the GS-14 and GS-15 levels are on the lower end than compared to Silicon Valley, but it's actually around what an engineer with similar experience can get in the DC/NoVA area, in my experience.
Not to mention that it's basically impossible to get fired as a GS unless you royally screw up. Usually this means committing a felony outside of work, or committing serial sexual harassment in the workplace, etc.
Yes some of the big boys are wasteful and overpriced, but I can ensure you that the federal government itself would be 5x worse, especially since, in DC, at least, the typical GS level employee has absolutely no experience in software engineering, and many times less authority to make good decisions.
Anyway, I've seen a few of these types of enterprises sprout up in the last 5 or 6 years in DOD land. They are sometimes referred to as 'boutiques' in contrast to the big players like BAE, Northrop, Lockheed, etc. They tend to have much younger engineers, SV type office environments, and a lot of hubris.
I'm currently making a good salary via cleaning up their MongoDB, Node, and bloated AngularJS messes that never performed half as well as the old systems running Java and a real RDBMS.