"Anonymous.I put the bit about being able to turn with the foot flat on the floor to prove it is and can be done."
It CAN be quite easily done, but IT ISN'T DANCED THAT WAY.
In place of an actual backwards pivot, champions are placing their foot pre-turned and then turning their body over the foot. They do not pivot their foot against the floor to any substantial degree. They do this other action instead. I'm sure they could dance a literal pivot, but they have CHOSEN NOT TO.
Again, I refer you to your video collection.
"Actually Latin dancers with their technique would do a better Pivot than some Modern dancers on step four of a Spin Turn."
Perhaps. But perhaps the reason modern dancer don't actually dance a pivot is that a pivot is not the most suitable action to use there.