That's it right there. Just this last weekend I was in a fish shop that had two walking catfish. and I asked what the hell they were and the shop owner said "just some odd colored cats" he knew nothing about them I asked how big they would get and he said "oh IDK a little larger then the biggest one" which was around 15"
Once I got home I looked for what this thing was and found out it was a walking catfish. then did a short search here and found they are suposed to be illegal in the US.
So money and ignorance. I mean We as hobbiest are supposed to know what we have in our tanks but If the LFS doesn't know anything about itand you buy it b/c its something you have never seen and it catches your eye. (we've all done it) it shouldn't be our fault b/c the shop owner didn't know what it was.