The burden of testing is enormous and nobody wants to pay for it. I know plenty of companies that barely test at all. All except the Googles of the world miss stuff regularly.
Irony here is that College Board's core business is testing.
Ironically, the service the College Board is selling ... is itself testing, just of a different kind.
Honestly this is the most stupid part. And I don't think College Board (or whoever made the site) didn't do any testing -- if that's the case the site should be way more broken. It's probably a problem of setting non-realistic test cases.