I think the background check for the purchase permits are a little more thorough than the NICS check for rifles. I've come to the conclusion that NC still has purchase permits so that counties can make $5 a pop off residents.
That's another problems with these crappy permits. Each county has different rules and different waiting times. In Wake county, they are ready a week from the day you apply. In Pitt county, they are ready the next day afternoon. Craven county will hand out permits within 10 minutes, even at the gun shows.
It doesn't take more than 10 minutes to run the check, some larger counties get a lot more traffic, so that might be why they require longer wait times.