According to the Wikipedia article, which may or may not be accurately stating things:
> Whilst original estimates from the DWP planned for the administration costs for the rollout of Universal Credit were £2.2billion, by August 2014 this estimate was revised to £12.8billion over its "lifetime". The cost has since increased to £15.8 billion.[29] At that date only 7,000 claimants were receiving UC, although there are now over 175,000.
The cost of the rollout is £15.8B. Its customer base is currently 175K. There's no indication that costs won't increase when the customer base increases by an order of magnitude. Besides simplifying Facebook's business model and operations (akin to calling Google just a big web scraper), you seem to be underestimating what's up ahead for UC, or you seem to think that software is just built and then maintains its value and functionality with no future costs whatsoever.
Going to the source suggests it's the estimated cost of the entire rollout from 2010-2021
That's an entire rollout which entails designing, building and operating a payments system in parallel with several different existing systems it replaces, all the extra non-dev staff needed to keep things running and identify who gets which payment entitlements when, and all the additional administrative costs, which presumably involves an awful lot of explaining to the public how their benefit entitlements have changed. Actual software development probably accounts for a relatively small proportion of that. The status quo admin costs £3.5bn per annum, so an extra billion a year actually isn't as big a deal as it sounds.
If we can simplify all that down to a "bloated Java app" then we can certainly dismiss Facebook as a PHP web forum and suggest that its running costs don't compare particularly favourably, even if it does serve an awful lot of ads.
Judging by the reports of delays and admin cockups, if anything the UK government has probably underspent.
I mean look I'm not trying to say that these aren't staggering amounts of money. I'm just trying to keep these numbers in perspective. 15billion pounds may be an insane amount of money but if we look around we start to find that it is typical not just of 'inefficient government' but of software in general.
