Facebook handles hundreds of millions of users per day. Including images and movies. Facebook’s problems are rarely technical. Healthcare.gov is essentially a CRUD app.
I’m sure Healthcare.gov contractors had a lot more bureaucracy and protocols they had to follow—especially security—regarding a project of this magnitude than a cubicle engineer at FB. Granted, the original launch was botched, trying to compare the two is apples and oranges.
FB needs good data and good security so that they can sell what they collect. If it could be obtained from FB without paying them, they wouldn’t last very long.