I believe NCNS is a viscous circle, feedback loop that just gets worse over time. Feel free to prove me wrong.
A provider who needs to put money on her table and food in her pockets will overbook knowing some fucktard will no show. If everyone shows she can just ghost someone.
Fucktards will double book so if plan A falls through they can go with plan B. Last minute bookings can be tough, if you have a plan B you can still get a nut.
No idea which one came first but they feed on each other, the more you get ghosted the more likely you are to double book and visa versa.