I'd also heard of it, but had no idea what it was about, when it was used (I'm too old to have learnt phonics here) or that it had a tagline. Explanation appreciated :0)
That said, I stand by my original post title as being entirely grammatically correct, if a little conversational. It's the, erm... present perfect. "It has not worked" suggests a continuing state of affairs - the consequences are still in play - rather than "it did not work" (simple past?) which puts the action, and its consequences, more squarely in the past. I don't know whether "it's not" or "it hasn't" is more common in the States, but here the former is perfectly normal.
(Caveat, I've never really learnt tense names other than when studying French - and that was a long time ago. But I think I've got the right ones here.)