Being handed impossible constraints (serve 250k simultaneous users, verify them all with the IRS, but the IRS service you have to talk to can only handle 1000 s

Being handed impossible constraints (serve 250k simultaneous users, verify them all with the IRS, but the IRS service you have to talk to can only handle 1000 simultaneous requests) isn't incompetence on the developer's part, and we don't know whether something like that isn't what's happening. The team that built this site (which has had no unintentional downtime, latency or server errors -- whatever code they wrote hasn't fallen over, it's just stranded most people on a "please wait" page when they try to register) has no power over systems at all the other agencies they have to work with.