It is simple process of elimination through record keeping, inspections and applied 3rd grade math.
For WC possesion limit of 4. Inspection 4 specimens 1 license = no poacher.
For CB. 2 males 2 females (WC already inspected and breeeding permit issued) inspection 2 clutches of eggs at 5 each inspection 10 eggs hatch 10 babies sold 10 reciepts issued inspection = no poacher; and here's where just a little work is required: 2 pet stores are in possesion of 30 specimens, all with reciepts. 10 reciepts were written by Jon Doe. Records are reviewed and John Doe was inspected and did in fact produce 10 specimens. 20 reciepts were written by Joe Blow. Records were checked and Joe Blow only produced 10 specimens. Joe Blow is the poacher, his permit is revoked, he is fined, and his snakes are confiscated.
A permit system can work just fine so long as there are inpections after capture, egg laying, hatching and sale. And so long a anyone selling or possesing can be inpected. The only exceptions are those who are completely underground and catching their own specimens and they must be captured in the field without a license.

