The hotline that proved to be a “not-line” pretty much sums up Mayor Bill de Blasio’s approach to governing: all show, no attention to delivery.

Last year, first lady Chirlane McCray proudly announced a new city hotline for victims of sex-trafficking or those who witness it. Yet a woman who answered at that number this week said it wasn’t the hotline.

The Post discovered the problem while reporting for its exposés on the trafficking scourge that’s destroying the lives of countless young girls in the city every day.

“A specially trained officer will answer [the hotline number], and every single report will be investigated by human-trafficking enforcement,” promised McCray.

Oops: “No, this is not the sex-trafficking hotline,” said the woman who picked up. Other advertised “hotline” numbers, one at the NYPD and another at the Brooklyn DA’s office, had similar problems.

On Thursday, the NYPD’s Phil Walzak insisted the department operates a “dedicated hotline” that’s “staffed 24-7 by highly experienced investigators.”

Police also say they couldn’t “replicate” the problem The Post reported. Sure: Once the story ran, fixing any issues was a must. If City Hall truly cared, a staffer would’ve found the trouble before it became a news story.

But this is all too typical for an administration that never seems to have its eye on the ball — denouncing the “Two New Yorks” even as mayoral aides, rushing to appease a series of lobbyist and special-interest demands, wind up OK’ing the notorious Rivington Street flip.

And as the Administration for Children’s Services is declining so badly that a whole series of tots die while on its radar.

Blaring out its affordable-housing work even as poor maintenance brings a winter of heat and hot-water outages at city projects.

Vowing to ensure that New Yorkers “get the [mental-health] treatment that they need” even as street homelessness soars and the seriously mentally ill go untreated.

Is progressivism really just an endless series of empty press releases?