The main thing is their status and the population in an area. I have a wild caught turtle, but they are fine status wise and the lake/ pond was about 100 meters around and I could (winter) catch about 10 a day, in my secret spot . Does that sound wrong? But to take a frog from an area witch they are scarce in is cruel.

I think that catching them to sell as pets is not as good as to sell them as a breeder in hopes that the pet trade in the future wont heavily rely on nature.