47k seems extreme, but "a developer could build it in a day" is focusing on the app itself and not anything else.
1) It's a government gig, they didn't need just a dev. There was likely a PM, a tester or two. Probably an analyst. There's inevitably documentation by the ream that goes into anything government.
2) Great, they built it. Where is it installed? How is it installed? So you gotta build that too. And document all of that.
3) It was originally 1.4mln? And then whittled down to 47k? So how much of that was a business analyst being paid to do that work to whittle down the requirements? those meetings add up fast.
4) Was this also that lovely brand of government work where they had to travel to a secure facility to do the work? What travel costs were in the 47k?