It wasn't reported, because it didn't go through the campaign. President Trump was advised by his attorney that Hush Money payments aren't permitted to be paid for by campaign funds. If he had been told otherwise, he would have contributed the money to his campaign instead, and had them cut a check to Stormy.
Its was no sweat off his balls either way,
Of course it didn't go through the campaign. Can you imagine paying off a porn star a few weeks before the election with campaign money? That's right, neither can I. He would be the dumbest criminal on the planet to do that, exposing the scandal right before the election. And, by not reporting it makes it doubly nefarious. Bottom line, not reporting the money is illegal and it hid the scandal between him and Stormy Daniels. How many would not have voted for him had they found out those weeks before?
So no, you'd have to be a retard to have paid that money through the campaign knowing that money was being used to hide an affair.