I have built such systems. Two of them. One for benefits administration (DB, DC, Life, and Health). The other is a test prep system for 11 million students.
This is not that hard. I cannot comprehend this cost. I cannot comprehend 1/10th this cost. The developers I know from those places cannot comprehend this cost. 300M users who log on once a year just isn't that much. Considering that less than 10% of the population will use it, that's about $20 a head. For 20 minutes of work. $60/ hr employees could do punch card entry over the phone for that.
Bet they even sprung for HANA. Idiots.